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

  1. The peak value of a sine wave is 200 V. Its average value is

  2. A.

     127.4 V

    B.

     141.4 V

    C.

     282.8 V

    D.

     200 V


  3. The product of apparent power and cosine of the phase angle between circuit voltage and current is

  4. A.

     True power

    B.

     Reactive power

    C.

     Volt-amperes

    D.

     Instantaneous power


  5. Which of the following waves has the highest value of peak factor ?

  6. A.

     Square wave

    B.

     Sine wave

    C.

     Half wave rectified sine wave

    D.

     Triangular wave


  7. In a purely inductive circuit

  8. A.

     Actual power is zero

    B.

     Reactive power is zero

    C.

     Apparent power is zero

    D.

     None of above is zero


  9. Pure inductive circuit takes power from the A.C. line when

  10. A.

     Applied voltage decreases but current increases

    B.

     Applied voltage increases but current decreases

    C.

     Both applied voltage and current increase

    D.

     Both applied voltage and current decrease


  11. The reactance offered by a capacitor to alternating current of frequency 50 Hz is 20 Q. If frequency is increased to 100 Hz, reactance becomes __________ ohms.

  12. A.

     2.5

    B.

     5

    C.

     10

    D.

     15


  13. Time constant of a circuit is the time in seconds taken after the application of voltage to each

  14. A.

     25% of maximum value

    B.

     50% of maximum value

    C.

     63% of maximum value

    D.

     90% of the maximum value


  15. Magnitude of current at resonance in R-L-C circuit

  16. A.

     Depends upon the magnitude of R

    B.

     Depends upon the magnitude of L

    C.

     Depends upon the magnitude of C

    D.

     Depends upon the magnitude of R, Land C


  17. Inductance of a coil Varies

  18. A.

     Directly as the cross-sectional area of magnetic core

    B.

     Directly as square of number of turns

    C.

     Inversely as the length of the iron path

    D.

     As A to C


  19. Two waves of the same frequency have opposite phase when the phase angle between them is

  20. A.

     360°

    B.

     180°

    C.

     90°

    D.

     0°