CSEC Section D- Waves past paper questions

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SECTION D –WAVES

1.

a) (i)

Sound is produced by vibrating systems.

Complete Table below by identifying the part of the instrument that vibrates to produce its sound

(b)

The following is a brief description of how a student estimated the speed of sound in air. Standing at a distance d,, 100m from a large wall, I clapped my hands, increasing in frequency until each clap just coincided with each echo heard. The time for 0 claps was measured and used to compute the round trip time t. The speed of sound was then calculated using distance d and the round trip time t.

i)

Why did he stand 100 m away from the wall instead of 10 m? ______________________________________________________________________ ______________________________________________________________________

ii)

Why were 50 claps used instead of 1 clap? ______________________________________________________________________ ______________________________________________________________________

iii)

Write an expression for the speed of sound, in terms of d and t. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(c)

During a recent thunderstorm, a clap of thunder was heard 12.5 s after the lightning flashed. The speed of sound is 340 m/s in air. How many kilometers away was the lightning strike? ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________

PHYSICS EXAM PREPARATION MARATHON 2005 HAMPTON

PREPARED BY : J J THOMAS

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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ paper 2 January 2005 2.

a) (i)

Complete the table below by placing a tick (

√) in the appropriate column(s) to

indicate the property of the given wave.

(b)

In a track race the starter of the race may be at some considerable distance from the runners. Consider the case where the distance between a runner and the starter is 40 m, calculate the time taken for the sound from the starter’s gun to reach the runner. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ (Speed of sound = 350 m/s)

(c)

The average speed of a world-class sprinter at the race may be 6 m/s. Traveling at that average speed, what distance could this sprinter have covered in the time taken for the sound to reach him? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 2004



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3.

a) (i)

Solar radiation at the earth’s surface consists mainly of electromagnetic waves in the wavelength range 0.3

µm to 3.0 µm. Name THREEE types of

electromagnetic radiation whose wavelengths lie within this range. ______________________________________________________________________ ______________________________________________________________________ (b)

Name ONE type of electromagnetic radiation whose wavelength is

i)

Lessthan0.3

ii)

Greater than 3.0

(c)

Name ONE property which these three types of radiation have in common.

µm _______________________________________________________ µm _____________________________________________________

_____________________________________________________________________ (d)

Calculate the frequency of electromagnetic radiation of wavelength 1.5 µm. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ( Velocity of electromagnetic waves in a vacuum = 3 x 108 m/s )

(e)

A monochromatic (single wavelength) beam of light enters a glass block whose refractive index is 1.5. Calculate the velocity of light in the block. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ Paper 2 (January 2004

4.

a) (i)

State the laws of reflection.

_______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ _____



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ii.

An object placed in front of a plane mirror as in the Figure below

iii.

Draw two r ays of l ight leaving p oint A o n the object and received by an o bserver at points between P and P’. Show how these rays appear to come from the image.

iv.

Explain how real and virtual images are formed. State whether the image of the object in the Figure above is real or virtual. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ __________________________________________________________________



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(b) (i)

The beam from a laser in Kingston, Jamaica is reflected from a plane mirror on a satellite. The reflected beam is received in Port of Spain, Trinidad. The figure below illustrates this situation diagrammatically\. On the diagram draw the normal from the mirror to the earth’s surface.

ii.

Use the information given on t he diagram to determine the angle of incidence of t he laser light on the mirror. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 2001

5.

This question is concerned with the properties of three kinds of waves

(a)

Speed, wavelength and frequency are properties of waves. Explain the meaning of each of these terms when used in connection with a sound wave. Wavelength _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ ___ Wave speed _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ ___ Frequency

_______________________________________________________________________ _______________________________________________________________________



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_______________________________________________________________________ ___

(b) (i)

The figure below represents a number of adjacent wavefronts of a w ater wave in a ripple tank.

Use the Figure above to determine the wavelength of the water wave ___________________________________________________________________ ii.

The figure below is the displacement vs time graph of a small leaf floating in the path of the water wave in (i)

Determine the frequency of the wave by using the Figure above. _______________________________________________________________________ _______________________________________________________________________ ________________________________________________________ iii.

Calculate the speed of the water wave. _______________________________________________________________________ _______________________________________________________________________ _______________________________________________________________________ ___________________________________________________________________

(c) (i)

The figure below shows a wave pulse at time t = 0, moving from left to right on the string.



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What is the amplitude of this wave? ____________________________________

ii.

The front of the pulse arrives at the position marked, X, at time t = 0.1 s. Sketch on the axes below, a displacement vs time graph for a small element of rope at X.

June 2000

6. (a)

A transverse wave on the surface of a liquid has a wavelength of 1.8 cm. Explain what is meant by a transverse wave and the wavelength of the wave. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(b)

The figure below is a displacement-time graph representing the wave described in part (a) above.

(i)

For this wave determine the Amplitude ______________________________________________________________

Frequency ______________________________________________________________ Speed __________________________________________________________________



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(ii)

The figures below show the same wave striking a plane reflecting surface and incident on a small gap in a plane, reflecting surface respectively. Complete the diagrams to show the wave (i) after reflection and (ii) after passing through the gap.

The Figure below shows the same wave approaching the gap, which has been increased, to five times its srcinal size. Complete the figure to show the wave wave after it has passed through the gap.

June 1999

7. (a)

The table below lists types of waves and their sources. Complete the table by filling in the blank spaces .

In the thir d column, state whether the waves are tran sverse or

longitudinal.

TypeofWave Infra-red radiation

Source

Transverseorlongitudinal?

Soundwaves

Loud-speaker TV transmitter Table 2



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(b)

The figure below shows a wave spreading out from the point S. The wave hits the barrier and is reflected. On the diagram, draw TWO reflected wavefronts and mark, with an X, the point from which they appear to come.

(c)

The figure below is a graph which represents the variation of the displacement, y, with time, t, as a wave passes a certain point.

(i)

Use the graph to find the amplitude of the wave. ____________________________________________________________ ____________________________________________________________

(ii)

How long does one complete cycle of the wave take? ____________________________________________________________ ____________________________________________________________

(iii)

Calculate the frequency of the wave. ____________________________________________________________ ____________________________________________________________ ____________________________________________________________



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(iv)

What other information would be needed to calculate the wavelength of the wave? _____________________________________________________________

(v)

On the fi gure ab ove dr aw another wave, which h as the SA ME am plitude but half the frequency. June 1998

8 (a)

The scale diagram, in the figure below, shows plane wavefronts incident on a barrier, which has a narrow gap in it.

(i)

Determine the wavelength of the waves before they reach the barrier. ______________________________________________________________________

(ii)

What will be the wavelength of the waves after they pass through the gap? ______________________________________________________________________

(iii)

Complete the figure below to show what happens to the waves.

(iv)

On the figure below, show what happens when the gap in the barrier is wider.



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(b)

Two speakers, vibrating in phase, are positioned some distance apart in an open space. The crests of the waves from the speakers are shown on the figure below.

(i)

Explain the term ‘constructive interference’. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(ii)

Mark, with the letter C, TWO places on the figure above where constructive interference is taking place.

(iii)

Explain the term ‘destructive interference’ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(iv)

Mark, with a letter D, TWO places on the figure above where destructive interference is occurring.

(v)

Describe what you would expect to hear as you walk along the line, PQ. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(vi)

If the two speakers were moved closer together, what effect would this have on w hat you hear as you walk along the line PQ? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

June 1997



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9 (a)

Light and sound are both forms of waves. State TWO differences between light waves and sound waves. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(b)

The d iagram ab ove sh ows a lo udspeaker a t the en d of a ro om wi th an o pen do or leading into another room. A sound of frequency 255 Hz is emitted.

(i)

Draw ON TH E DI AGRAM a representation of t he s ound wa ve em erging from th e

(ii)

door. Why is someone standing at Point T able to hear but not able to see the loudspeaker? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(iii)

If the speed of sound is 340 m/s, calculate the wavelength of the sound waves. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(c)

In a storm the lightning is often seen a considerable time before the thunder is heard.

(i)

Account for this fact. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________



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(ii)

If the lightning is seen 8 s econds before the thunder is h eard, calculate the distance of the thundercloud from the observer. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(iii)

What assumption have you made in your calculation in (ii) above? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 1994

10.

Short wavelength radio waves (microwaves) have many applications, e.g. in w eather stations.

(i)

The radar used in weather stations transmits microwaves of frequency 3 x 10

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Hz.

These are emitted in pulses EACH of 1.0 x 10 -6s duration. Calculate

– the wavelength of the radiation -

the number of waves emitted in a pulse

[ Speed of electromagnetic waves = 3 x 108 m/s] (ii)

The power of the transmitter is 200 KW. What is the total energy in a pulse? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(iii)

After the emission of a pulse, nothing is transmitted for one millisecond. Calculate how far the pulse travels in this time. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(iv)

To detect a distant object, the pulse is reflected from it and must return to the weather station before another pulse is emitted. What is the furthest distance at which an object may be detected using this system? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 1993



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11 (a)

The diagram below shows a plane water waves incident on a gap.

(i)

Draw the waves after they have passed through the gap.

(ii)

What name is given to this effect?

(b)

Some sound systems have three loudspeakers to cater for the full range of frequencies to be transmitted. The following table gives the wavelength ranges for three speakers and frequency.

(i)

From the information given for the squawker, calculate the velocity of sound. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(ii)

Determine the missing frequency range and insert it in the table above. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ A loudspeaker such as that motioned in (i) and (ii) is positioned in a corridor, 1 metre wide as shown in the diagram below. An observer notices that when she stands at X, she hears equally well from the three speakers. However, when she stands at Y, she hears mainly from one speaker and much less from the others.



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(iii)

From which speaker does she hear most sound when standing at Y? ______________________________________________________________________

(iv)

With reference to the data in the table and diagram above, give an explanation for her observations while at Y. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(c)

The wavefronts shown in the diagrams below represent three different sounds.

Compare the loudness and pitch of i)

PandQ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

QandR ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________



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iii)

Explain in what other way sounds P and Q differ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 1992

12.

.

(a)

Label the parts A, B, C, D in the diagram of the eye above. The eye in the figure above is long-sighted. By drawing rays on the diagram show how the long-sightedness is corrected with the use of the converging lens.

(b)

The spectacle lens used in the diagram above has a focal length of 80 cm. It produces a virtual image of the object being viewed. If the object is 10 cm high and 40 cm from the lens find, by completing the scale drawing below, the position and magnification of the image.

June 1991



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13. (a)

The figure below represents a transverse wave on a string vibrating with a frequency of 100 Hz

i)

State the amplitude and wavelength of the wave. Amplitude ______________________________________________________________ Wavelength _____________________________________________________________

ii)

Calculate the period and velocity of the wave ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

b. (i)

.

The diagrams in the figure above show series of plane wavefronts approaching (i) a narrow gap and (ii) a wide gap. Complete the diagrams to show the wavefronts after have passed through EACH gap. (c)

The figure below shows plane electromagnetic wavefronts

travelling in air with

velocity of 3.0 x 10 8 m/s, and meeting a plane refracting surface at an angle of 30 °. The wavelength of the waves in air is 4.0 x 10 second medium is 2.2 x 108 m.

-7

m and the velocity of the waves in the



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Calculate: i)

The frequency of the wave in air. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

The wavelength of the waves in the second medium and the angle of refraction ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ June 1990

14. (a)

.

The diagram above, drawn to scale, shows plane wavefronts before and after refraction at an air-glass boundary.



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i)

Find the refractive index of the glass for these waves. Clearly show on the diagram above all measurements made. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

What is the value of the angle of incidence of these wavefronts? ______________________________________________________________________

(b)

Light is incident at 60° at an air-water boundary and is refracted at 40 °, as shown in the Figure below.

i)

Calculate the refractive index of water. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

Draw a w avefront to represent this refraction at a n air-water boundary. (Your diagram need not be to scale) Mark, on the diagram, the size of the angle between the incident wavefronts and the boundary, and also between the refracted wavefronts and the boundary



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c. (i)

The functioning of a human eye depends on refraction. Name the TWO parts of the eye where refraction takes place. ______________________________________________________________ ______________________________________________________________

ii)Explain why the amount of refraction at one of the two parts is much greater than that at the other. _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _________________________________________________________________ _______ June 1989 PAPER THREE

1. (a)

Describe an experiment to verify the laws of reflection. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

The figure below is a magnified view of the cross section of one track of a compact disk (CD) and its read head.

Information is stored on the CD as a series of ‘hills’ and ‘valleys’ stamped into the aluminium mirror. The information is read by shining light from a laser source at X through the clear plastic layer so that it is reflected towards the sensor at Y, which has a very tiny opening. i)

If the la ser light b eam fo llows th e pa th sh own in t he fi gure be low, ca lculate th e refractive index of the clear plastic.

______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ 5 marks

ii)

The tr ack moves to t he le ft (read he ad do es no t mo ve) so t hat EF be comes the reflecting surface ( see the figure above). With the aid of a diagram showing the beam reflected from surface EF through the plastic and into the air, explain why the emerging beam will miss the sensor. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 7 marks total 20 marks June 2004

2. (a)

With the aid of a neat cl early-labelled diagram, describe an expe riment to sho w that when light is reflected from a plane surface the angle of incidence and angle of reflection are equal. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ (b)

8 marks Some Internet Source Providers (companies that provide connection to the Internet and

are known as ISP’s) communicate with their customers via line-of-sight microwave links. A microwave antenna at the customer’s premises should be able to ‘see’ the ISP’s antenna in order that the customer can carry on two-way communication with the Internet. Consider such a link operating at 2.5 x 10

9

Hz with 30 km between customer site and

ISP antenna.

i)

What is th e wa velength and pe riod of th e mi crowave signal be tween customer an d provider? (The velocity of light C = 3 x 108 m/s. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

Calculate in microseconds the time it takes for a signal to travel between customer and

provider and back again to customer.



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ iii)

Explain why the customer may still have communication even if her antenna is u nable to see the ISP’s antenna directly. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 12 marks total 20 marks June 2003

3. (a)

Describe an experiment to verify Snell’s law of refraction. State what apparatus you would use, give a brief description of the method you would use and state how you would arrive at your conclusion. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

8 marks



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(b)

An optical device consists of two glass blocks of different indices of refraction, arranged as shown in the figure below. The refractive index from air to Medium 1 is 1.2. The refractive index from Medium 1 to Medium 2 is 1.25.

i)

If light is incident at 60

° on the block with the smaller refractive index, determine the angles θ1, θ2, θ3,θ4, and θ5. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ii)

What is the velocity of light in Medium 1? c = 3 x 10

8

m/s.

______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 12 marks Total 20 marks June 2002

4. (a)

Describe a sim ple experiment for measuring the sp eed of s ound in ai r. Give ONE method of improving the accuracy of your measurements. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

A loudspeaker is driven by an amplified audio signal so that its cone oscillates at

500 Hz. i)

Determine the wavelength and period of the sound produced.



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ii)

If the distance between the points of m aximum displacement of t he cone is 0 .6 cm, sketch a well-labelled displacement-time graph for the motion of the cone. Indicate on your graph the points of maximum and minimum cone velocity.

(speed of sound =

350 m/s) ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ iii)

If the maximum displacement of the cone is increased, what is the effect on the

(a)

Loudness of the sound? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

(b)

Frequency of the sound? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 12 marks Total 20 marks June 2001

5. (a) (i)

Explain with the aid of a diagram, how the human eye forms an image. ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ii)

State the characteristics of the image formed and compare the properties of this image with that formed by a diverging lens. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

.

The figure above shows a thick-bottomed, glass aquarium containing water. A beam of light from a submerged source, S, is incident on the base at point X. the angle of incidence at X is 58 °. If the refractive index of light going from water to glass is 1.13, calculate the i)

angle of refraction in the glass ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ii)

critical ang le for li ght striking th e gla ss to air bo undary. (r efractive in dex for ai r to glass = 1.50) ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 marks

(c)

use the angles you have calculated to draw a diagram showing the path of the refracted beam after it leaves X. Partial reflection also occurs at X. Draw the reflected ray on your diagram.

6 marks Total 20 marks June 2000

6. (a)

with the aid of ray diagrams explain the terms ‘refractive index’ and ‘critical angle’. Draw a ray diagram to show how a right-angled isosceles glass prism can be used to turn a ray of light through 180

°, and identify an optical instrument that utilises this

property. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

b. (i)

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a ray of light travelling in water at a speed of 2.25 x 10 m/s strikes the water surface as in the figure below. Determine the refractive index of the water and calculate the maximum angle the beam can make with the normal if the light is to enter the air. (Speed of light in air = 3.00 x 108 m/s)

______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 marks

ii)

the light source is replaced by a detector of light, and a ray is then shone on the surface o the water form the air. Is there any angle of incidence at which no light enters the water? Explain. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ 3 marks

(c)

the figure below shows three rays entering a specially shaped piece of glass called a prismatic window. The angle of incidence of the two outer rays on the surfaces AB and CD is greater than the critical angle for glass. Copy and complete the diagram to show the passage of the rays through the window.

3 marks total 20 marks June 1999

7. (a)

sometimes light is treated as waves and other times it is represented by straight lines or rays.

i)

Describe, with the aid of a d iagram, an e xperiment to s how that light does consist of waves. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 marks

ii)

Explain the term ‘diffraction’.



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ iii)

Light can b e treated as ra ys travelling in st raight lines because diffraction is us ually negligible. Explain why this is so, an give an example of an observation or demonstration which supports the view that light travels in straight lines. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ (b)

.

Data : Speed of light in air Speed of light in glass

= 3. 0 x 108 m/s = 1.9 x 10

8

m/s

Wavelength of light in air = 1.2 x 10-6 m The diagram above illustrates the way light travels through a glass fibre. The ray of light stays within the glass because of repeated total internal reflection. Ues the data provided to answer the following questions. i)

Calculate the refractive index of t he glass and find the smallest possible value f or angle, i, if the light is to undergo total internal reflection. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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5 marks

ii)

Calculate the frequency of the light in air and the frequency and wavelength of the light in the glass fibre. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 7 marks total 20 marks June 1998

8.

The diagram below shows a boy doing his homework. He h as difficulty reading his book under the small light bulb.

(a)

In your answer booklet, draw a ray diagram to show the shadow produced by his head on the table. What dif ference would it make to the shadow if the ligh t bulb were replaced by a long fluorescent tube? Draw a diagram to illustrate this case. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 marks

(b)

Light is form of electromagnetic (e.m.) waves. Name THREE other types of e.m. waves and state which of the three has the longest wavelength. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 marks

c. (i)

Low-frequency e.m. radiation is used to communicate with submarines. The frequency used is 30 Hz. If the speed of e.m. waves in air is 3.0 x 10 8 m/s, what is the wavelength of the low-frequency radiation in air? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

A beam of low-frequency radiation is incident upon the surface of the sea at an angle of 15° as shown in the diagram below.

If the speed of the radiation is reduced to 2.5 x 10 8 m/s in water, determine the angle of refraction. What is the wavelength and frequency of the radiation in water? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 marks

iii)

If radiation of the same frequency is emitted by the submarine which is under water, at what angle of incidence would total internal reflection occur in the sea. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 marks total 20 marks June 1997

9. (a) (i)

Draw a ray dia gram to sho w the for mation of an imag e by a dive rging lens. State, with ONE reason, whether you think the image is virtual or real. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 marks

ii)

One defect of the eye is ‘short-sight’. Explain what this term means. Draw a ray diagram to show how a diverging lens may be used to correct this defect. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

4 marks



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(b)

When a converging lens forms a real image of an object, the magnification of the image can be calculated from the equation Magnification = image distance/object distance With the aid of a ray diagram, show that this relationship is true.

3 marks

(c)

A converging lens is used to form a real image of an object placed 15 cm away from it. Given that the image is twice as high as the object, by means of a scale drawing, determine the focal length of the lens. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 9 marks total 20 marks June 1996

10. (a)

Given a straight vibrator and a rip ple tank, describe how you would demonstrate the reflection and refraction of water waves. Draw diagrams to represent what would be observed in EACH case. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

Ultra-sound (high frequency sound) is used in medicine to perform internal investigations upon patients. As the ultra-sound passes from muscle into bone, some is refracted. The diagram below represents a beam of ultra-sound incident upon a muscle/bone boundary.

When a wave, travelling at a speed, v1, strikes a boundary at an angle of incidence, θ1, the relation between its angle of reflection,

θ2, and its speed in the next medium, v2 is

given by: sinθ1/sinθ2 = v1/v2 The table below shows the speed of ultra-sound in certain media:

i)

The ultra-sound used has a frequency of 8.0 x 10

6

Hz. Calculate the wavelength of the

ultra-sound in bone. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 marks

ii)

Use the information in the table to calculate the angle of refraction in the bone. Copy and complete the diagram to show what happens to the ultra-sound.



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

5 marks

iii)

Ultra-sound can be totally reflected at certain boundaries. What is the critical angle for ultra-sound incident upon the muscle-bone boundary? Is total reflection possible as ultra-sound, travelling in muscle, meets the air? Explain your answer. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 marks total 20 marks June 1995

11. (a) (i)

In terms of the wave theory, explain why refraction of light occurs. Illustrtae your answer with a labelled diagram. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ii)

4 marks With the aid of ray diagram, explain the terms ‘refractive index’ and ‘critical angle’. ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ (b)

4 marks A ray of light hits a block of ice at P, as shown in the diagram below. The refractive index of ice is 1.6.

i)

Calculate the angle of refraction of the light incident at P. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 3 marks

ii)

Calculate the value of the critical angle for ice. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ 3 marks



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iii)

Draw a l arge diagram to s how the path of t he r ay of light through the ice. Mark the sizes of the angles of incidence and show clearly where the ray leaves the ice.

6 marks total 20 marks June 1994

12. (a)

Newton investigated light and obse rved that light of several colours appeared on a screen when white light was passed through a prism. Use fully labelled diagrams to illustrate how Newton used two prisms to show that

i)

The different colours were merely components of white light and not the result of the interaction of white light with the material of the prism. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

Any single colour produced by one prism could NOT be split into other clours. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

A converging lens of focal length 10.0 cm is used in a projector to form an enlarged image of a slide on a screen. The slide is 4.0 cm high and is placed 12.0 cm from the

lens. Determine by scale drawing on graph paper (i) the position at which the screen should be placed to receive a sharp image and (ii) the size of the image.



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 7 marks

(c)

In some older people, the eye lens becomes opaque. This condition is known as a cataract and is sometimes corrected by removal of the eye lens. Use a diagram to illustrate what effect this removal will have on the eye’s ability to form images on the retina and state what type of spectacle lens may correct this problem. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 marks Total 20 marks June 1993

13. (a)

Describe, with the aid of a diag ram, an inves tigation to meas ure the cr itical angle of glass or perspex. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________



42

______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

An object is at the bottom of a water-filled tank. When it is viewed from above it does not appear to be at its actual position. Draw a ray diagram to illustrate this and state what is observed. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 marks

(c)

.

The figure above represents a ray of light leaving a light pipe through the face YZ. The light ray is incident at M at an angle of 68 ° to the normal. Given that the critical angle is 42° for the glass-air interface, calculate i)

the refractive index of the glass ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

the angle of refraction at the face YZ. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



43

8 marks Total 20 marks June 1992

14. (a)

Describe, with the aid of diag rams where ap propriate, observations which le ad us to believe that:

i)

Light has wave properties. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

ii)

The wavelength of light is much smaller than the wavelength of sound. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks

(b)

Plane sound waves travelling IN AIR are incident, at an angle, on a flat water surface. Their wavelength is 5.0 m. The speed of sound in air id 300 m/s, but it increases to 1500 m/s. Draw a diagram showing the approximate directions and wavelengths of the waves as they cross the air-water boundary. Calculate the frequency and wavelength of sound waves in the water. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ 7 marks

(c)

The sound waves can only enter the water if the angle of incidence is small enough. Account for this observation and calculate the maximum size of the angle of incidence for the sound to enter the water. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 marks June 1991

15. (a)

The table below shows the values for frequency and wavelength of certain waves, A, B and C, travelling on deep sea water.

Wavelength/m Frequency/Hz

A

B

C

10

1.5

6

4

1

0.5

Calculate the speed of the waves in EACH case and state TWO ways in which the speed of deep sea waves differs from that of electromagnetic waves in a vacuum. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 5 marks

(b)

A circular wave-front is created by dropping a stone in a lake. Suggest TWO reasons why the amplitude of the wave-font decreases as it spreads out. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________

______________________________________________________________________ 3 marks



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(c)

Sound waves are used in echo sounding to find the depth of the sea at different places e.g. under oil-rigs. The sound wave sent out at the surface of the sea is reflected from the sea bed and the time taken for the echo to return is measured. Near an oil-rig, the echo returns in 4.6 seconds. If the speed of sound in water is 1500 m/s, calculate the depth of the sea near this oil rig. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 marks

(d)

State TWO conditions necessary for total internal reflection to occur. Draw a diagram showing sound waves striking an air-water boundary at the critical angle. (Represent the sound by a ray.) Calculate the value of the critical angle Speed of sound in air

= 300 m/s

Speed of sound in water

= 1500 m/s

______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 8 marks June 1990

16. (a)

With reference to a converging lens, what is meant by the term ‘ focal length’? ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 2 marks

(b)

By means of well-labelled diagrams, show how a converging lens can form (i) a REAL IMAGE and (ii) a VIRTUAL IMAGE. Give a practical example of a useful application of EACH type of image.

______________________________________________________________________ ______________________________________________________________________



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______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 6 marks

(c)

An object placed 20 cm from a converging lens and along its axis produces an image 60 cm from the lens. Determine by scale drawing, the focal length of the lens if the image is formed on the opposite side of the lens from the object. ( Use graph paper)

(d)

If the object were now placed 60 cm from the lens, state where the image would be formed and what its height would be, relative to that of the object. ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ ______________________________________________________________________ 4 marks June 1989



CSEC Section D- Waves past paper questions

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