10A

R 20Ω 100V

100Ω

Q.1 For the given circuit the value of R such that the same amount of power is supplied to the 100Ω by the current and voltage source will be R = ---------

Q.2 For the given circuit the thevenin’s voltage and thevenin’s resistance between A and B will be(i)20/3V, 16Ω (ii) 16V, 20/3 Ω

(iii) 20/3 V, 14Ω (iv) None of these

ANSWER-

3. (i) R/3, R, R/2

ANSWER-

4. (iv) zero

(i) 63/18 Ω (ii) 63/28 (iii) 63/65 (iv) None of these

ANSWER-

5. (iv) None of these

(i) 4Amp (ii) zero (iii) 2Amp (iv) 1Amp

ANSWER-

8. (ii) zero

ANSWER-

9. (iv) BOTH (i) & (ii)

ANSWER-

10. (ii) 1.2Ω

Q.11 The instantaneous voltage and current for an ac circuit are

V = 180.8 sin388t Volt, I = 8.95 sin(388t – 36.87)A. The phaser diagram will be

ANSWER-

11. (i)

Q.12 A series RLC circuit has the following parameter, R = 10Ω, L = 0.01H, C = 100µF. The quality factor of the circuit at resonance is

(i) 1 (ii)2 (iii)3 (iv)4

ANSWER-

12. (i) 1

Q.13 If resonant frequency of the circuit in fig. 1 is 1KHz. The resonant frequency of the circuit shown in fig. 2 will be

(i) 4KHz (ii) 2KHz (iii) 0.5KHz (iv) 0.25Hz

ANSWER-

13. (iii) 0.5KHz

Q.14 If power factor of circuit is unity its reactive power is

(i)zero (ii) maximum(iii) equal to I2R (iv) a negative quantities

ANSWER-

14. (i) zero

Q.15 In series R-C circuit as frequency increases

(i)current decreases (ii) current remain same

(iii) current increase (iv) None of these

ANSWER-

15. (iii) current increase

Q.16 A single phase 50Hz motor takes 20A at 0.75pf lagging from a 230V sinusoidal supply. If a capacitor is connected in parallel to raise the power factor to 0.9 lagging. The new supply current is

(i)16.67A (ii) 15.67A(iii) 14.67A (iv) 15A

ANSWER-

16. (i) 16.67A

Q.17 The voltage and current through circuit elements are V = 100 sin(314t + 45), I = 10 sin(314t +315)A. The circuit elements will be

(i)L (ii) R(iii) C (iv) None of these

ANSWER-

17. (i) L

Q.18 An iron choke coil takes 4A when connected to a 20V dc supply and takes 5A from 65V, 50Hz ac supply. The inductive reactance of coil will be

(i)14Ω (ii) 16Ω(iii) 18Ω (iv) 12Ω

ANSWER-

18. (iv) 12Ω

Q.19 A resistor of 25Ω is connected in parallel with capacitor where capacitive resistance is 40Ω. The parallel circuit is connected across 100V, 50Hz supply. The total current drown from the supply is

(i)6.5A (ii) (4 + j2.5)A

(iii) (4 – j2.5)A (iv) (2.5 + j4)A

ANSWER-

19. (ii) (4 + j2.5)A

Q.20 In star connected 3ф system , the angle between the line current and the corresponding line voltage is equal to

(i)30 + ф (ii) 120 + ф(iii) 90 + ф (iv) None of these

ANSWER-

20. (i) 30 + ф

Q.21 Three 100Ω resistors are connected in delta across 400V, 3 phase supply, if one of the resistor disconnected then the phase current will

(i)4/√3 A (ii) 4√3 A(iii) 4 Amp (iv) None of these

ANSWER-

21. (iii) 4 Amp

Q.22 Three similar coils each having a resistance of 8 and inductance of 0.0191H in series in each phase is connected across 400V, 3ф 50Hz supply ( Assume system is connected in star). The input power will be

(i)14.8Kw (ii) 12.8Kw

(iii) 10Kw (iv) 16Kw

ANSWER-

22. (ii) 12.8Kw

Q. 23 In a balanced 3ф delta connected system the relation between phase current and line current (IL) is

(i)Iph = √3 IL (ii) Iph = IL/2

(iii) Iph = IL/√2 (iv) Iph = 0.577 IL

ANSWER-

23. (iv) Iph = 0.577 IL

Q.24 In a 3ф power measurement by two wattmeter method, the reading of one of the wattmeters was -ve. The power factor of the load must be

(i)Greater then 0.5 (ii) less then 0.5(iii) equal to 0.5 iv) -ve

ANSWER-

24. (ii) less then 0.5

Q.25 Two wattmeter method is used to measure the power taken by a 3ф induction motor on No load. The wattmeter readings are 375W and -50W. The power factor of motor at no load will be

(i)0.404 lag (ii) 0.5 lag(iii) unity pf (iv) 0.85 lag

ANSWER-

25. (i) 0.404 lag

Q.26 Energy meter is

(i)An indicating Instrument (ii) Integrating Inst. (iii) recording Inst. (iv) Absolute Inst.

ANSWER-

26. (ii) Integrating Inst.

Q.27 The value of resistance required to extend the range of voltmeter is given by the relation

(i)R = Rm/m-1 (ii) R = Rm/m+1

(iii) R = (m-1)Rm (iv) R = (m+1)Rm

ANSWER-

27. (iii) R = (m-1)Rm

Q.28 In three phase circuit for zero power factor, the power measured by two watt meter is

(i)2 watt (ii) zero(iii) 4 watt (iv) 6 watt

ANSWER-

28. (ii) zero

Q. 29 The Norton’s equivalent of circuit consists of 2A current source in parallel with 4Ω resistance the thevenin’s equivalent voltage and thevenin’s resistance will be equal to

(i)8V, 4Ω (ii) 2V, 6Ω

(iii) 0.5V, 4Ω (iv) 2V, 0Ω

ANSWER-

29. (i) 8V, 4Ω

Q.30 For the given circuit the mesh equation will be

(i)V1 + V2 + V3 + V4 = I1R1 + I1R2 – I1R3 – I1R4 – I1R5 (ii)- V1 - V2 + V3 + V4 = I1(R1+R2+R3+R4+R5)(iii) V1 + V2 - V3 + V4 = I1(R1+R2+R3+R4+R5)(iv) None of these

ANSWER-

30. (ii) - V1 - V2 + V3 + V4 = I1(R1+R2+R3+R4+R5)

Q .31 If frequency of power supply in pure inductive circuit is doubled. The current will be

(i)doubled (ii) half

(iii) remains same (iv) None of these

ANSWER-

31. (ii) half

Q.32 The admittance of circuit is represented by (8 + j10) which implies that the circuit is

(i)Inductive (ii) Capacitive

(iii) purely capacitive (iv) none of these

ANSWER-

32. (ii) Capacitive

Q.33 The dynamic impedance of R-L-C parallel circuit at resonance in given by

(i)C/LC (ii) LC/R(iii) R/LC (iv) L/CR

ANSWER-

33. (ii) LC/R

Q.34 The order in which voltage in 3 phase reach their maximum +ve value is called

(i)phase sequence (ii) phase angle(iii) peak value (iv) None of these

ANSWER-

34. (i) phase sequence

Q.35 The force responsible for reduction of oscillation of pointer in an ammeter is

(i)compelling force (ii) damping force (iii) deflecting force (iv) None of these

ANSWER-

35. (ii) damping force