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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGQuestion Bank

Programme : BESubject : EE6201-CIRCUIT THEORY

Semester / Branch : II/EEE,ECE &EIEUNIT-IPART-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.

Examine the instantaneous value of voltage and current. (B.L.T- 3)4. Summarize the classifications of Circuit elements (B.L.T- 2)5. Analyze how are the following affected by change of frequency

a) Resistance b) Inductive reactance. (B.L.T- 4)6. Define ideal voltage source (B.L.T- 1)7. Define active elements and passive elements. (B.L.T- 1)8. Distuinguish between series and parallel circuit (B.L.T- 2)9. Select the value of R1 and R2 when they are parallel with the following

conditions. The current in R1 is twice the current flowing through R2 andthe 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 inseries across an AC voltage supply. If a current of 0.9 A is flowing in thecircuit calculate the power factor. (B.L.T- 3)

12.Measure the equivalent conductance Geq of the circuit shown below(B.L.T- 5)

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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING

13.Two inductances L1=3mH and L2=6mH are connected in parallel.Analyse and infer Leq (B.L.T- 4)

14.Compose the equivalent resistance for the following combination ofresistor and source current (B.L.T- 6)

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

16.Define power factor. (B.L.T- 1)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 – B1. Interpret the current delivered by the source shown in the circuit below.


DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING(B.L.T- 2)

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

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 ohmresistor in the circuit shown in figure (B.L.T- 1)

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


VALLIAMMAI ENGINEERING COLLEGE EE6201- CIRCUIT THEORY

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VALLIAMMAI ENGINEERING COLLEGESRM NAGAR, KATTANKULATHUR – 603203


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

6. Use Nodal Voltage method and estimate the power dissipated in the 10Ω 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 ofCurrent (8 marks) (B.L.T- 1)

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 andcurrent are i=28sin(314+60º) and e=180 sin 314t formulate and obtain a) theRMS value of the voltage and current b) the frequency c) the power factor d)the power e) the values of circuit constants. (B.L.T- 6)

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-IIPART-A

1. Explain how voltage source with a source resistance can beconverted into an equivalent current source. (B.L.T- 4)

2. Analyse the current flowing through the resistors R1 and R3 ifcurrent through R2 is 1A (B.L.T- 4)

3. Calculate The Equivalent Current Source for a Voltage Source Of10v In Series With A 60ohm Resistance. (B.L.T- 3)

4. Illustrate the equivalent voltage source for a current source of 15A



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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGwhen connected in parallel with 5 ohm resistance (B.L.T- 3)

5. Given that the resistors Ra, Rb and Rc are connected electrically instar. 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 theexpression for resistors in equivalent star (B.L.T- 6)

7. How will you express the Norton’s equivalent circuit from Thevenin’sequivalent circuit? (B.L.T- 2)

8. State Superposition theorem (B.L.T- 1)9. Describe the theorem used in converting an electrical circuit into one

equivalent resistance in series with voltage source (B.L.T- 1)10.Identify the theorem used in converting an electrical circuit into one

equivalent resistance in parallel with current source (B.L.T- 1)11. State Maximum power transfer theorem (B.L.T- 1)12.Define reciprocity theorem (B.L.T- 1)13.A voltage source has internal impedance (4+j5) ohm. Measure the load

impedance for Maximum power transfer (B.L.T- 5)14. Is reciprocity theorem applied to the circuit having resistors, capacitors

and diodes? Give your reason (B.L.T- 2)15.Three resistors A,B and C are connected in parallel and takes 2.5

A,IB=2IC Interpret(a) IB and IC (b)the line voltage and (c)RB and RC(B.L.T- 2)

16. Describe the concept of current division in a circuit. (B.L.T- 1)17.Using superposition theorem, calculate current in the circuit. (B.L.T- 3)

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

PART-B1. 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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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING2. 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 bridgecircuit of figure. Calculate i)the equivalent resistance between P&Qii)the total current (iii)the current through the 18Ω resistor (B.L.T- 3)

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

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) Ωimpedance by using Superposition theorem. (8 marks) (B.L.T- 2)

(ii) Discuss in detail and prove that, in a pure resistive circuit,RL=RThusing Maximum power transfer theorem. (8 marks) (B.L.T- 2)

7. Give Thevenin’s equivalent across the terminals AB for the circuit shownin figure below. (B.L.T- 2)

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



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

(ii) Define and explain reciprocity theorem. (8 marks) (B.L.T- 1)

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

UNIT-IIIPART-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

coupling(k) between the two coils 0.6 as shown in fig. (B.L.T-3)

4. Define quality factor of a series resonant circuit. (B.L.T-1)



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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING5. 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)7. Design the frequency response of double tuned circuit. (B.L.T-6)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)12. Define bandwidth of a resonant circuit. (B.L.T-1)13.Give the applications of tuned circuits. (B.L.T-2)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 thiscircuit. (B.L.T-4)

15.When do you say that a given AC circuit is at resonance? (B.L.T-1)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 inductivelycoupled circuits with self inductance L1=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-B1. With neat illustration and necessary derivations, describe the linear

transformer (B.L.T-1)2. Define and derive the mutual inductance and the coupling coefficient of

the transformer with necessary illustration. (B.L.T-1)3. Impedance Z1and Z2 are parallel and this combination is in series with an

impedance Z3 connected to a 100V, 50 Hz ac supply. Z1=(5-jXc) ohm,



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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGZ2=(5+j0) ohm, Z3=(6.25+j1.25) ohm. Analyse the value of capacitancesuch that the total current of the circuit will be in phase with the totalvoltage. Find the circuit current and power. (B.L.T-4)

4. The switch in the circuit shown in fig is moved from position 1 to 2 att=0. Evaluate the expression for voltage across resistance and capacitor,energy in the capacitor for t>0 (B.L.T-5)

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

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 andthe Q factor of the circuit. (8 marks) (B.L.T-2)

(ii) The number of turns in two coupled coils are 500 turns, 1500 turnsrespectively. When 5A current flows in coil 1, the total flux in this coil is0.6* 10-3 Wb and the flux linking the second coil is 0.3*10-3Wb.Calculate L1, L2, M and K. (8 marks) (B.L.T-3)

8. (i) A coil having an inductance of 100mH is magnetically coupled toanother coil having an inductance if 900mH. The coefficient of coupling



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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERINGbetween the coils is 0.45. Predict the equivalent inductance if the twocoils are connected in (4+4 marks) (B.L.T-2)

a) Series aiding and Series opposingb) Parallel aiding and Parallel opposing (8)

(ii) What are coupled circuits? Sketch the frequency response of a singletuned circuit and give the explanation of tuned circuits.

(B.L.T-6) (8 marks)9. For a series RLC circuit: Derive the condition for resonance, explain the

frequency response and also obtain quality factor and bandwidth.(B.L.T-4)

10. Discuss the following (B.L.T-2)(i) Co-efficient of coupling (8 marks)(ii) Tuned circuit (8 marks)

UNIT-IVPART-A

1. Define Step function? (B.L.T-1)2. Describe an initial condition? (B.L.T-1)3. Define transient? (B.L.T-1)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

of q=0. (B.L.T-6)12. Develop an equivalent circuit for inductor and capacitor at t=0+ when

there is no initial energy. (B.L.T-6)13. A coil having a resistance of 10 K 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 togive critical damping. (B.L.T-3)

15. Distinguish between transient response and steady state response of acircuit. (B.L.T-2)



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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING16. A series RL with R=100 and L=20H has a dc voltage of 200V applied

through a switch at t=0. Assuming the initial current through the inductorat t=0 is zero, evaluate the current at t=0.5sec (B.L.T-5)

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 , Z21=120 , Z12=120 , Z22=50 .

Calculate Y parameters. (B.L.T-3)

PART-B1. Express the step responses of RL and RC circuits. Compare their

performances. (B.L.T-2)2. Give the expression for current response of RLC series circuit with

sinusoidal excitation. Assume that the circuit is working in criticaldamping condition. (B.L.T-2)

3. (i) A series RC circuit with R=5 K and C=20uF as a constant voltagesource of 100V applied at t=0; there is no initial charge on the capacitor.Examine the current i and charge q for t > 0 (8 marks) (B.L.T-1)(ii) In the circuit given below, the switch has been in position 1 forsufficient time to establish steady state conditions. The switch is thenmoved to position 2.show the current transient (8 marks) (B.L.T-3)

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

(8 marks) (B.L.T-5)5. (i) Using laplace transform analyze expression for i1 and i2 in the circuit

shown below, when dc voltage source is applied suddenly. Assume thatinitial energy stored in the circuit is zero. (8 marks)( B.L.T-4)



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

6. In the circuit shown describe about the expression for current if theswitch is closed at t=0 and the value of current at t=1ms. Assume initialcharge on the capacitor is zero (B.L.T-1)


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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING7. In the series circuit shown in figure, the switch is closed on position 1 at

t=0. At t=1ms, the switch is moved to position 2. Interpret the equationsfor the current in both intervals and draw the transient current curve.

(B.L.T-2)

8. A series RC circuit with R=100 and C=25uF is supplied with a sourceof 200Sin(500t) volt. Express the current in the circuit. Assume initialcharge on the capacitor is zero. (B.L.T-2)

9. (a) Examine the transient response of series RLC circuit with DC inputusing laplace transform. (B.L.T-1)

i. Derive the necessary differential equation and solve.ii. Discuss the cases of over damping, Critical damping and

under damping(b) In a T network shown in fig Z1=2 0°, Z2=5 -90°, Z3=3 90°,calculate the Z parameters (8 marks) (B.L.T-3)

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


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(B.L.T-2)







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(B.L.T-2)








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(ii) Express Y parameters of network shown in fig from Z parameters.(8 marks) (B.L.T-2)

UNIT-VPART-A

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

2. List the advantages of 3Φ system over 1Φ (B.L.T-1)3. List out the methods of power measurement in 3Φ circuits (B.L.T-1)4. Give the distortion power factor equation of three phase circuits. (B.L.T-1)5. List out the methods of power measurement in 3Φ circuits.(B.L.T-1)6. Identify the voltage across Y and B in a 3 Φ balanced delta system with

voltage across R and Y is 400�00 V. Assume RYB phase sequence(B.L.T-1)

7. Distinguish between unbalanced source and unbalanced load. (B.L.T-2)8. Give the equations for the phasor difference between the potentials of the

delta connected networks. (B.L.T-2)9. A 3Φ 400V supply is given to a balanced star connected load of

impedance 8+j6 ohms in each branch. Estimate the line current (B.L.T-2)10.A 3Φ motor can be regarded as a balanced Y load. A 3Φ motor draws

5.6kW when the line current is 18.2A. Estimate the power factor of themotor (B.L.T-2)


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UNIT-VPART-A









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UNIT-VPART-A










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DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING11. In the measurement of three phase power using two wattmeter method,

predict when both the wattmeter read same values, what is the value ofpower factor of the load? (B.L.T-2)

12.Describe measurement of reactive power using wattmeter. (B.L.T-2)13.Three coils, each having resistance of 20 and an inductive reactance of

15 are connected in star to a 400V, 3Φ and 50Hz supply. Calculate a)line current, b) power factor and c) power supplied. (B.L.T-3)

14.Calculate the power factor if V(t)=Vmsin(ωt-450) and I(t)=Imsin(ωt-1350)(B.L.T--3)

15. Calculate the power factor if V(t)=Vmsinωt and I(t)=Imsin(ωt -450)(B.L.T--3)

16.Explain balance supply system. (B.L.T-4)17. In two wattmeter power measurement method, if one wattmeter reads

zero, analyze the power factor of the circuit. (B.L.T-4)18.Compare star and delta connected system. (B.L.T-4)19. Summarize the main objectives of interconnection of the phases?

(B.L.T-5)20.Develop the circuit diagram for balanced delta connected load. (B.L.T-6)

PART-B1. Discuss in detail about the three phase 3-wire circuits with star connected

balanced loads. (B.L.T-2)2. Explain in detail the phase diagram of voltages and currents of a three

phase unbalanced loads. (B.L.T-5)3. A symmetrical three phase three wire 440v supply to a star connected

load. The impedance in each branch are =2+j3 , =1-j2 and=3+j4 . Calculate its equivalent delta connected load. (B.L.T-3)

4. A three phase balanced delta connected load of 3+j4 is connectedacross a 400v, 3 phase balanced supply. Examine the phase currents andline currents (Phase sequence in RYB). (B.L.T-1)

5. A balanced delta connected load takes a line current of 15 A whenconnected to a balanced 3 phase 400 v system. A wattmeter with itscurrent coil in one line and Potential coil between the two remaining linesread 2000W. Describes the load impedances. (B.L.T-1)

6. Develop the expression for balanced delta connected load and draw thephasor diagram. (B.L.T-6)


DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING7. Explain three phase power measurement by 2 wattmeter method for star

and delta connected load and determine the power equation and draw thephasor diagram. (B.L.T-4)

8. Give the short notes on symmetrical components and un-symmetricalcomponents. (B.L.T-1)

9. The two wattmeter methods produces wattmeter readings P1=1560W andP2=2100W When connected to delta connected load. If the line voltage is220V, Calculate (1) the per phase average power (2) the per phasereactive 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 powerfactor in the three phase circuits (B.L.T-2)BLOOM’S TAXONOMY

PART A BTL 1 BTL 2 BTL 3 BTL 4 BTL 5 BTL 6UNIT 1 6 4 3 3 2 2UNIT 2 6 4 3 3 2 2UNIT 3 6 4 3 3 2 2UNIT 4 6 4 3 3 2 2UNIT 5 6 4 3 3 2 2Total 30 20 15 15 10 10

PART B BTL 1 BTL 2 BTL 3 BTL 4 BTL 5 BTL 6UNIT 1 3 2 1 2 1 1UNIT 2 3 2 1 2 1 1UNIT 3 3 2 1.5 2 1 0.5UNIT 4 3 2 1 2 1 1UNIT 5 3 2 2 1 1 1Total 15 10 5.5 9.5 5 5


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