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EEE :: A.C Fundamentals, Circuits and Circuit Theory

  1. The r.m.s. value of pure cosine function is

  2. A.

     0.5 of peak value

    B.

     0.707 of peak value

    C.

     Same as peak value

    D.

     Zero

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  3. The phosphors for which of the following pair are 180° out of phase for VL, VC and VR?

  4. A.

     VC and VR

    B.

     VL and VR

    C.

     VC and VL

    D.

     None of the above

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  5. The r.m.s. value of half wave rectified sine wave is 200 V. The r.m.s. value of full wave rectified AC. will be

  6. A.

     282.8 V

    B.

     141.4 V

    C.

     111 V

    D.

     100 V

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  7. In an AC. circuit, a low value of kVAR compared with kW indicates

  8. A.

     Low efficiency

    B.

     High power factor

    C.

     Unity power factor

    D.

     Maximum load current

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  9. If two sinusoids of the same frequency but of different amplitudes and phase angles are subtracted, the resultant is

  10. A.

     A sinusoid of the same frequency

    B.

     A sinusoid of half the original frequency

    C.

     A sinusoid of double the frequency

    D.

     Not a sinusoid

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  11. If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave?

  12. A.

     42.42 sin 314 t

    B.

     60 sin 25 t

    C.

     30 sin 50 t

    D.

     84.84 sin 25 t

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  13. The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is

  14. A.

     4 kVAR

    B.

     6 kVAR

    C.

     8 kVAR

    D.

     16 kVAR

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  15. What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value?

  16. A.

     0°

    B.

     45°

    C.

     90°

    D.

     180°

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  17. The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of

  18. A.

     Iron loss in core

    B.

     Skin effect

    C.

     Increase in temperature

    D.

     Capacitive effect between adjacent coil turns

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  19. Power factor of an inductive circuit is usually improved by connecting capacitor to it in

  20. A.

     Parallel

    B.

     Series

    C.

     Either A or B

    D.

     None of the above

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