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Tuesday, 15 December 2015

Parallel A.C. Circuits - Multiple Choice Questions

Parallel A.C. Circuits - Multiple Choice Questions Points : parallel a.c. circuits, multiple choice questions and answers, electrical objective type question answers, mcqs 1. In a parallel a.c. circuit. power loss in due to ……..
(i) conductance alone
(ii) susceptance alone
(iii) both conductance and susceptance
(iv) none of the above

2. Domestic appliances are linked in parallel across a.c. mains as …………
(i) It is a simple arrangement
(ii) operation of each appliance becomes free of the other
(iii) appliances have same currents ratings
(iv) this arrangement occupies less space

3. The power taken through circuit shown in Fig. 1 is
(i) 480W
(ii) 1920W
(iii) 1200 W
(iv) none of the above
4. The active part of line current in Fig. 1 is ……..
(i) 8A
(ii) 4A
(iii) 5.3 A
(iv) none of the above

5. The power factor of circuit shown in Fig. 1 is
(i) 0.707 tagging
(ii) 0.5 lagging
(iii) 0.866 lagging
(iv) none of the above

6. The power obsessive in circuit shown in Fig. 2 is
(i) 480 W
(ii) 960 W
(iii) 1200 W
(iv) none of the above
7. The active part of line current in Fig. 2 is
(i) 6 A
(ii) 3 A
(iii) 13 A
(iv) 4 A

8. The line current drawn through circuit shown in Fig. 2 is
(i) 13 A
(ii) 6 A
(iii) 5 A
(iv) none of the above

9. The power factor of circuit shown in Fig. 2 is ………..
(i) 0.8
(ii) 0.5
(iii) 0.707
(iv) none of the above

10. The impedance of circuit shown in Fig. 2 is ……….
(i) 180 ohms
(ii) 24 ohms
(iii) 48 ohms
(iv) none of above

11. The circuit shown in fig 2 is ……….
(i) resistive
(iii) capactive
(iii) inductive
(iv) in resonance

12. If in Fig. 2 XL is made equivalent to XC then line current will be …………
(i) 10A
(ii) 6 A
(iii) 4 A
(iv) none of above

13. If the circuit shown in Fig. 3 is linked to 120 V dc., current drawn through the circuit is ………
(i) 24A
(is) 70A
(iii) 48 A
(iv) 30 A
14. The power extreme in circuit in Fig. 3 is ……….
(i) 8400W
(ii)3600 W
(iii) 4000 W
(iv) none of the above

15. The circuit shown in Fig. 3 is
(i) capacitive
(ii) inductive
(iii) resistive
(iv) in resonance

16. If the source rate in Fig. 4 is low, then ……..
(i) coil takes a high lagging current
(ii) coil takes a low lagging current
(iii) capacitor takes a high leading current
(iv) circuit offers high impedance
17. If the source frequency in Fig. 4 is high, then …………
(i) coil takes a high lagging current
(ii) capacitor takes a high leading current
(iii) capacitor takes a low leading current
(iv) circuit offers high impedance

18. The conductance and susceptance components of admittance are
(i) series elements
(ii) parallel elements
(iii) series-parallel elements
(iv) none of the above

19. If the access of a parallel ac. Circuit is amplified, the circuit current
(i) remains constant
(ii) is decreased
(iii) is increased
(iv) none of the above

20. The conductance and inductive susceptance of a circuit contain the similar magnitude. The power factor of circuit is ……..
(i) 1
(ii) 0.5
(iii) 0.707
(iv) 0.866

21. While a parallel a.c. circuit contains a number of branches, then it is suitable to solve the circuit by
(i) phasor diagram
(ii) phasor algebra
(iii) equivalent impedance method
(iv) none of the above

22. A circuit has an impedance of (1 – j 2) Ω. The Susceptance of circuit is ……….
(i) 0.1 S
(ii) 0.2 S
(iii) 0.4 S
(iv) none of the above

23. The access of a parallel circuit is 0.12 ,-30°—3O° S. The circuit is ………
(i) inductive
(ii) capacitive
(iii) resistive
(iv) in resonance

24. The impedance of a circuit is 10 ohm.s. If inductive susceptance is 1 S. then inductive reactance of circuit is …………
(i) 10 Ω
(ii) 1 Ω
(iii) 100 Ω
(iv) none of the above

25. The impedance at parallel resonance is extremely large because …………..
(i) R is very large
(ii) ratio C/L is very large
(iii) ratio L/C is very large
(iv) none of the above

26. At parallel resonance, circuit offers impedance equivalent to
(i) L/CR
(ii) LC/R
(iii) RL/C
(iv) CR/L

27. A circuit has admittance of 0.1 S and conductance of 0.08 S. The power factor of circuit is
(i) 0.1
(ii) 0.8
(iii) 0.08
(iv) none of the above

28. In a parallel ac. circuit, if supply frequency Ii lass than the resonant frequency then the circuit is ………..
(i) inductive
(ii) capacitive
(iii) resistive
(iv) none of the above

29. In a parallel ac. circuit, if supply frequency is more than the resonant frequency, after that the circuit is ……….
(i) resistive
(ii) inductive
(iii) capacitive
(iv) none of the above

30. If a parallel resonant circuit is shunt through a resistance, then ……………..
(i) circuit impedance is decreased
(ii) Q of the circuit is increased
(iii) the gain of the circuit is increased
(iv) none of the above

31. A parallel resonant circuit magnifies …….
(i) voltage
(ii) current
(iii) both voltage and current
(iv) none or the above

32. At parallel resonance, circuit draws a current of 2 mA. If the Q of circuit is 100, then current through the capacitor is ……….
(i) 2mA
(ii) 1 mA
(iii) 200 mA
(iv) none of the above

33. In a parallel RC circuit by R > XC the phase angle will be
(i) 45°
(ii) greater than 45°
(iii) 90°
(iv) insufficient data

34. The Q-factor of a parallel tune circuit can be enlarged by ………
(i) increasing circuit resistance
(ii) decreasing circuit resistance
(iii) decreasing inductance of the circuit
(iv) none of the above

35. If resistance in the inductive branch of a parallel resonant circuit is amplified, then, ………….
(i) the circuit impedance is increased
(ii) Q of the circuit is increased
(iii) selectivity of the circuit is increased
(iv) impedance of the circuit is decreased

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