EE6201 Circuit Theory

VALLIAMMAI ENGINEERING COLLEGE EE6201- CIRC CIRCUIT UIT THEORY

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VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULAT KATTANKULATHUR HUR – – 603203 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

Question Bank Programme

: BE

Subject

: EE6201-CIRCUIT THEORY

Semester / Branch

: II/EEE,ECE &EIE UNIT-I PART-A

1. Define Ohm’s Law (B.L.T- 1) 2. List and define Kirchoff’s Laws for electric circuits. (B.L.T- 1) 3. An 1Φ 50 Hz ac supply system has the RMS values of 100V, 10 A. (B.L.T- 3) Examine the instantaneous value of voltage and current. (B.L.T- 2) 4. Summarize the classifications of Circuit elements 5. Analyze how are the following following affected affected by change of frequency (B.L.T- 4) a) Resistance b) Inductive reactance. 6. Define ideal voltage source (B.L.T- 1) (B.L.T- 1) 7. Define active elements and passive elements. (B.L.T- 2) 8. Distuinguish Distuinguish between series and parallel circuit 9. Select the value of R1 and R2 when they are parallel with the following conditions. conditions. The current in R1 is twice the current flowing through through R2 and the equivalent resistance of the parallel combination is 10/3Ω. (B.L.T- 5) 10. Point out the magnitude of currents in the Ammeter of resistance 10Ω (B.L.T- 4)

11. A resistance of 120Ω and a capacitive reactance of 250Ω are connected in series across an AC voltage supply. If a current of 0.9 A is flowing in the (B.L.T- 3) circuit calculate the power factor. 12. Measure the equivalent conductance G eq of the circuit shown below (B.L.T- 5)

VALLIAMMAI ENGINEERING COLLEGE EE6201- CIRCUIT THEORY

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VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULATHUR – 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

13. Two inductances L1=3mH and L2=6mH are connected in parallel. (B.L.T- 4) Analyse and infer Leq 14. Compose the equivalent resistance for the following combination of (B.L.T- 6) resistor and source current

15. Generalize the expressions for mesh current equations in matrix form (B.L.T- 6) (B.L.T- 1)

16. Define power factor. 17. Describe the term phasor (B.L.T- 1) 18. Differentiate active and reactive power in electrical circuits (B.L.T- 2) 19. How do you differentiate Power and Energy in Electrical Circuits? (B.L.T- 2)

20. Calculate the power absorbed by each of the elements in a given circuit. (B.L.T- 3)

PART – B

1. Interpret the current delivered by the source shown in the circuit below.


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VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULATHUR – 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING (B.L.T- 2)

2. For the network shown below, label the current ratio (I1/I3) by applying (B.L.T- 1) mesh analysis.

3.

Tabulate a) the equivalent resistances across the terminals of the supply, b) total current supplied by the source and c) power delivered to 16 ohm (B.L.T- 1) resistor in the circuit shown in figure

4. Analyze the mesh currents I1 and I2 for the given circuit shown below (B.L.T- 4)


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5. Determine the value of V2 such that the current through the impedance (B.L.T- 3) (2+j3) ohm is zero

6. Use Nodal Voltage method and estimate the power dissipated in the 10 Ω resistance on the circuit shown in the fig (B.L.T- 2)

7. (i) Derive and list the expressions for resistors in series and parallel (8 marks)

(B.L.T- 1)

(ii) Quote the Kirchoff’s current law and prove it by using the definition of (8 marks) (B.L.T- 1) Current 8. Calculate loop currents by mesh analysis (B.L.T- 3)


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9. In a circuit consisting of two elements in series, the equations for voltage and current are i=28sin(314+60º) and e=180 sin 314t formulate and obtain a) the RMS value of the voltage and current b) the frequency c) the power factor d) (B.L.T- 6) the power e) the values of circuit constants. 10. Evaluate the current in each branch and total power consumed by the circuit. Assume E = 50 sin (ωt+45). (B.L.T- 5)

UNIT-II PART-A

1. Explain how voltage source with a source resistance can be (B.L.T- 4) converted into an equivalent current source. 2. Analyse the current flowing through the resistors R1 and R3 if (B.L.T- 4) current through R2 is 1A

3. Calculate The Equivalent Current Source for a Voltage Source Of (B.L.T- 3) 10v In Series With A 60ohm Resistance. 4. Illustrate the equivalent voltage source for a current source of 15A


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VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULATHUR – 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING (B.L.T- 3) when connected in parallel with 5 ohm resistance

5. Given that the resistors Ra, Rb and Rc are connected electrically in star. Formulate the equations for resistors in equivalent delta. (B.L.T- 6) 6. Three resistors Rab, Rbc and Rca are connected in delta. Re-write the (B.L.T- 6) expression for resistors in equivalent star 7. How will you express the Norton’s equivalent circuit from Thevenin’s (B.L.T- 2) equivalent circuit? 8. State Superposition theorem (B.L.T- 1) 9. Describe the theorem used in converting an electrical circuit into one (B.L.T- 1) equivalent resistance in series with voltage source 10. Identify the theorem used in converting an electrical circuit into one (B.L.T- 1) equivalent resistance in parallel with current source 11. State Maximum power transfer theorem (B.L.T- 1) (B.L.T- 1) 12. Define reciprocity theorem 13. A voltage source has internal impedance (4+j5) ohm. Measure the load (B.L.T- 5) impedance for Maximum power transfer 14. Is reciprocity theorem applied to the circuit having resistors, capacitors (B.L.T- 2) and diodes? Give your reason 15. Three resistors A,B and C are connected in parallel and takes 2.5 A,IB=2IC Interpret(a) I B and IC (b)the line voltage and (c)R B and RC

Describe the concept of current division in a circuit. 17. Using superposition theorem, calculate current in the circuit. 16.

(B.L.T- 2) (B.L.T- 1) (B.L.T- 3)

18. Discuss some applications of maximum power transfer theorem (B.L.T- 2) (B.L.T- 4) 19. Point out the limitations of superposition theorem? (B.L.T- 5) 20. Convince the purpose of star delta transformation. PART-B

1. Deduce the expressions for star connected arms in terms of delta connected arms and delta connected arms in terms of star connected arms (B.L.T- 5)


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2. Determine the Thevenin’s equivalent for the figure and develop the Norton’s equivalent from the same (B.L.T- 6)

3. Using star-delta transformation, in the following wheat stone bridge circuit of figure. Calculate i)the equivalent resistance between P&Q (B.L.T- 3) ii)the total current (iii)the current through the 18Ω resistor

4. Using source transformation, replace the current source in the circuit shown below by a voltage source and solve for the current delivered by (B.L.T- 3) the 50V source

5.

Analyze the given circuit and obtain Norton’s equivalent circuit (B.L.T- 4)


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6. (i) For the circuit shown below, express the voltage across (2+j5) Ω (8 marks) (B.L.T- 2) impedance by using Superposition theorem.

(ii) Discuss in detail and prove that, in a pure resistive circuit,R L=RTh (8 marks) (B.L.T- 2) using Maximum power transfer theorem. 7. Give Thevenin’s equivalent across the terminals AB for the circuit shown (B.L.T- 2) in figure below.

8. Using superposition theorem identify the current through (2+j3) (B.L.T- 1) ohm impedance branch of the circuit shown.


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9. (i) Examine the value of RL so that maximum power is delivered to (8 marks) (B.L.T- 1) the load resistance shown in figure.

(ii) Define and explain reciprocity theorem.

(8 marks) (B.L.T- 1)

10. Examine and identify the maximum power delivered to the load in the (B.L.T- 1) circuit

UNIT-III PART-A

1. Define mutual inductance. (B.L.T-1) 2. Express the dot rule. (B.L.T-2) 3. Calculate the total inductance of the circuit, if the coefficient of (B.L.T-3) coupling(k) between the two coils 0.6 as shown in fig.

4.

Define quality factor of a series resonant circuit.

(B.L.T-1)


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5. Illustrate the quality factor of a coil for the series resonant circuit consisting of R= 10 ohm, L= 0.1 henry and C= 10 micro farad .(B.L.T-3) 6. Define quality factor Q of a coil (B.L.T-1) (B.L.T-6) 7. Design the frequency response of double tuned circuit. 8. Describe bandwidth of the circuit? (B.L.T-2) 9. Define coefficient of coupling. (B.L.T-1) 10. Design the frequency response of RLC series circuit. (B.L.T-6) 11. Give the expression which relates the self and mutual inductance .(B.L.T-2) (B.L.T-1) 12. Define bandwidth of a resonant circuit. (B.L.T-2) 13. Give the applications of tuned circuits. 14. A series resonance circuit has a bandwidth of 20kHz and a quality factor of 40. The resistor value is 10k ohm. Evaluate the value of L of this (B.L.T-4) circuit. (B.L.T-1) 15. When do you say that a given AC circuit is at resonance ? 16. Analyse resonant frequency in terms of half power frequencies .(B.L.T-4) 17. Judge, When the power is maximum in the series resonance circuits? Why? (B.L.T-5) 18. Examine

the maximum possible mutual inductance of two inductively coupled circuits with self inductance L 1=25mH and L2=100mH. (B.L.T-3) 19. Compare the properties of series and parallel resonant circuits. (B.L.T-4) 20. Deduce the resonant frequency and quality factor for the circuit shown (B.L.T-5)

PART-B

1. With neat illustration and necessary derivations, describe the linear (B.L.T-1) transformer 2. Define and derive the mutual inductance and the coupling coefficient of (B.L.T-1) the transformer with necessary illustration. 3. Impedance Z1and Z2 are parallel and this combination is in series with an impedance Z3 connected to a 100V, 50 Hz ac supply. Z 1=(5-jXc) ohm,


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Z2=(5+j0) ohm, Z 3=(6.25+j1.25) ohm. Analyse the value of capacitance such that the total current of the circuit will be in phase with the total (B.L.T-4) voltage. Find the circuit current and power. 4. The switch in the circuit shown in fig is moved from position 1 to 2 at t=0. Evaluate the expression for voltage across resistance and capacitor, (B.L.T-5) energy in the capacitor for t>0

5. For the circuit shown in fig., calculate the impedance at resonant frequency, 10Hz above resonant frequency, and 10Hz below resonant (B.L.T-3) frequency

6. Describe how to derive Q factor of parallel resonance (B.L.T-1) 7. (i) For the circuit shown below, express the frequency at which the circuit resonates. Also calculate the voltage across the inductor at resonance and the Q factor of the circuit. (8 marks) (B.L.T-2)

(ii) The number of turns in two coupled coils are 500 turns, 1500 turns respectively. When 5A current flows in coil 1, the total flux in this coil is -3 -3 0.6* 10 Wb and the flux linking the second coil is 0.3*10 Wb. (8 marks) (B.L.T-3) Calculate L1, L2, M and K. 8. (i) A coil having an inductance of 100mH is magnetically coupled to another coil having an inductance if 900mH. The coefficient of coupling


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between the coils is 0.45. Predict the equivalent inductance if the two (4+4 marks) (B.L.T-2) coils are connected in a) Series aiding and Series opposing b) Parallel aiding and Parallel opposing (ii) What are coupled circuits? Sketch the frequency response of a single tuned circuit and give the explanation of tuned circuits. (8 marks) (B.L.T-6) 9. For a series RLC circuit: Derive the condition for resonance, explain the frequency response and also obtain quality factor and bandwidth. 10. Discuss the following (i) Co-efficient of coupling (ii) Tuned circuit

(B.L.T-4) (B.L.T-2) (8 marks) (8 marks)

UNIT-IV PART-A

1. Define Step function? (B.L.T-1) (B.L.T-1) 2. Describe an initial condition? (B.L.T-1) 3. Define transient? 4. Describe steady state value ? (B.L.T-1) 5. List the periodic inputs? (B.L.T-1) 6. Quote the term time constant of a transient response . (B.L.T-1) 7. Give time constant of a RL & RC circuit . (B.L.T-2) 8. Distinguish between free and forced response . (B.L.T-2) 9. Describe about Critical damping ? (B.L.T-1) 10. Analyze the current given by I (t) = 5 – 4 e-20t (B.L.T-4) 11. Design the equivalent circuit at t=0+ for a capacitor with initial charge of (B.L.T-6) of q=0. 12. Develop an equivalent circuit for inductor and capacitor at t=0+ when (B.L.T-6) there is no initial energy . 13. A coil having a resistance of 10 K Ω and inductance of 50mH is connected to a 10 volts, 10KHz power supply. Calculate the impedance (B.L.T-3) 14. In a series RLC

circuit, L=2H and C= 5uF. Calculate the value of R to (B.L.T-3) give critical damping. 15. Distinguish between transient response and steady state response of a (B.L.T-2) circuit.


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and L=20H has a dc voltage of 200V applied through a switch at t=0. Assuming the initial current through the inductor (B.L.T-5) at t=0 is zero, evaluate the current at t=0.5sec 17. Define a two port network (B.L.T-1) 18. Discuss z- and y- parameter of a typical four terminal network .( B.L.T-2) 19. Summarize h parameter and give its applications. (B.L.T-2) 20. In a two port network, Z11=100 Ω, Z21=120Ω, Z12=120Ω, Z22=50Ω. (B.L.T-3) Calculate Y parameters. 16. A series RL with R=100Ω

PART-B

1. Express the step responses of RL and RC circuits. Compare their (B.L.T-2) performances. 2. Give the expression for current response of RLC series circuit with sinusoidal excitation. Assume that the circuit is working in critical (B.L.T-2) damping condition. 3. (i) A series RC circuit with R=5 KΩ and C=20uF as a constant voltage source of 100V applied at t=0; there is no initial charge on the capacitor. (8 marks) (B.L.T-1) Examine the current i and charge q for t > 0 (ii) In the circuit given below, the switch has been in position 1 for sufficient time to establish steady state conditions. The switch is then (8 marks) (B.L.T-3) moved to position 2.show the current transient

4. (i) Analyze the expression for current transient when series RL circuit is (8 marks) (B.L.T-4) excited by a sinusoidal source v=Vm(sin ωt) at t=0 (ii)A series RLC circuit with R=50Ω, L=0.1H and C=50uF as a voltage of 100V applied to it at t=0 through a switch. Evaluate the expression for a current transient. Assume initially relaxed circuit conditions (8 marks) (B.L.T-5)

5. (i) Using laplace transform analyze expression for i 1 and i2 in the circuit shown below, when dc voltage source is applied suddenly. Assume that (8 marks)( B.L.T-4) initial energy stored in the circuit is zero.


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VALLIAMMAI ENGINEERING C LLEGE SRM NAGAR, KATTANKULATHUR – 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS E GINEERING

(ii) In the circuit s hown below examine the expression for the transient (8 marks) (B.L.T-1) current. The initial current is shown in the figure

6. In the circuit sho n describe about the expression f r current if the switch is closed at t=0 and the value of current at t=1m . Assume initial (B.L.T-1) charge on the capa itor is zero


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7. In the series circui shown in figure, the switch is closed on position 1 at t=0. At t=1ms, the switch is moved to position 2. Interp ret the equations for the current in b th intervals and draw the transient cur rent curve. (B.L.T-2)

8. A series RC circui with R=100Ω and C=25uF is suppli d with a source of 200Sin(500t) v lt. Express the current in the circuit . Assume initial (B.L.T-2) charge on the capa itor is zero. 9. (a) Examine the transient response of series RLC circuit with DC input (B.L.T-1) using laplace trans orm. i. Deriv the necessary differential equation an d solve. ii. Discu s the cases of over damping, Critical damping and under damping (b) In a T network shown in fig Z 1=2∟0°, Z2=5∟- 0°, Z3=3∟90°, (8 marks) (B.L.T-3) calculate the Z par meters

10. (i) Evaluate the Z arameters for the circuit shown in fig (8 marks) (B.L.T-5)


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(ii) Express Y para meters of network shown in fig from

parameters. (8 marks) (B.L.T-2)

UNIT-V PART-A

1. Describe the effect of power factor in energy consumptio billing (B.L.T-1) (B.L.T-1)

2. List the advantages of 3Φ system over 1Φ 3. List out the metho s of power measurement in 3Φ circuit (B.L.T-1) 4. Give the distortion power factor equation of three phase c ircuits. (B.L.T-1) 5. List out the metho s of power measurement in 3Φ circuit .(B.L.T-1) 6. Identify the voltag across Y and B in a 3 Φ balanced delta system with 0 voltage across R a d Y is 400 ∠0 V. Assume RYB phase sequence 7. Distinguish betwee n unbalanced source and unbalanced l 8. Give the equations for the phasor difference between the delta connected net works. 9. A 3Φ 400V sup ly is given to a balanced star co impedance 8+j6 oh ms in each branch. Estimate the line c 10. A 3Φ motor can be regarded as a balanced Y load. A 5.6kW when the li ne current is 18.2A. Estimate the po motor

(B.L.T-1) (B.L.T-2)

ad. potentials of the (B.L.T-2)

nected load of rrent (B.L.T-2) Φ motor draws er factor of the (B.L.T-2)


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VALLIAMMAI ENGINEERING COLLEGE SRM NAGAR, KATTANKULATHUR – 603203 DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING 11. In

the measurement of three phase power using two wattmeter method, predict when both the wattmeter read same values, what is the value of (B.L.T-2) power factor of the load ? (B.L.T-2) 12. Describe measurement of reactive power using wattmeter . 13. Three coils, each having resistance of 20 Ω and an inductive reactance of 15Ω are connected in star to a 400V, 3 Φ and 50Hz supply. Calculate a) (B.L.T-3) line current, b) power factor and c) power supplied. 0 0 14. Calculate the power factor if V(t)=V msin(ωt-45 ) and I(t)=Imsin(ωt-135 ) 15. Calculate the power factor if V(t)=V msinωt

and I(t)=Imsin(ωt

(B.L.T--3) 0 -45 ) (B.L.T--3) (B.L.T-4)

16. Explain balance supply system . 17. In two wattmeter power measurement method, if one wattmeter reads (B.L.T-4) zero, analyze the power factor of the circuit. 18. Compare star and delta connected system. (B.L.T-4) 19. Summarize the main objectives of interconnection of the phases ? 20. Develop the circuit diagram for balanced delta

(B.L.T-5) connected load . (B.L.T-6)

PART-B 1.

2. 3.

4.

5.

6.

Discuss in detail about the three phase 3-wire circuits with star connected (B.L.T-2) balanced loads. Explain in detail the phase diagram of voltages and currents of a three (B.L.T-5) phase unbalanced loads. A symmetrical three phase three wire 440v supply to a star connected load. The impedance in each branch are =2+j3Ω, =1-j2Ω and =3+j4Ω. Calculate its equivalent delta connected load. (B.L.T-3) A three phase balanced delta connected load of 3+j4 Ω is connected across a 400v, 3 phase balanced supply. Examine the phase currents and (B.L.T-1) line currents (Phase sequence in RYB). A balanced delta connected load takes a line current of 15 A when connected to a balanced 3 phase 400 v system. A wattmeter with its current coil in one line and Potential coil between the two remaining lines (B.L.T-1) read 2000W. Describes the load impedances. Develop the expression for balanced delta connected load and draw the (B.L.T-6) phasor diagram.


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7. Explain three phase power measurement by 2 wattmeter method for star and delta connected load and determine the power equation and draw the (B.L.T-4) phasor diagram. 8. Give the short notes on symmetrical components and un-symmetrical (B.L.T-1) components. 9. The two wattmeter methods produces wattmeter readings P 1=1560W and P2=2100W When connected to delta connected load. If the line voltage is 220V, Calculate (1) the per phase average power (2) the per phase reactive power. (3) the power factor (4) the phasor impedance. (B.L.T-3) 10. Describe about the various methods to measure the real power and power (B.L.T-2) factor in the three phase circuits BLOOM’S TAXONOMY

PART A

BTL 1

BTL 2

BTL 3

BTL 4

BTL 5

BTL 6

UNIT 1

6

4

3

3

2

2

UNIT 2

6

4

3

3

2

2

UNIT 3

6 6

4 4

3 3

3 3

2 2

2 2

Total

6 30

4 20

3 15

3 15

2 10

2 10

PART B

BTL 1

BTL 2

BTL 3

BTL 4

BTL 5

BTL 6

UNIT 1 UNIT 2

3 3

2 2

1 1

2 2

1 1

1 1

UNIT 3

3

2

1.5

2

1

0.5

UNIT 4

3 3 15

2 2 10

1 2 5.5

2 1 9.5

1 1 5

1 1 5

UNIT 4 UNIT 5

UNIT 5 Total

EE6201 Circuit Theory

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