A.C. Fundamentals, Circuits and Circuit Theory MCQ

Practice Test: Question Set - 10


1. The peak value of a sine wave is 200 V. Its average value is
    (A) 127.4 V
    (B) 141.4 V
    (C) 282.8 V
    (D) 200 V

2. The inductance of a coil can be increased by
    (A) Increasing core length
    (B) Decreasing the number of turns
    (C) Decreasing the diameter of the former
    (D) Choosing core material having high relative permeability

3. For a sine wave with peak value Imax the r.m.s. value is
    (A) 0.5 Imax
    (B) 0.707
    (C) 0.9
    (D) 1.414 Imax

4. For a frequency of 200 Hz, the time period will be
    (A) 0.05 s
    (B) 0.005 s
    (C) 0.0005 s
    (D) 0.5 s

5. The ratio of active power to apparent power is known as factor.
    (A) Demand
    (B) Load
    (C) Power
    (D) Form

6. The best place to install a capacitor is
    (A) Very near to inductive load
    (B) Across the terminals of the inductive load
    (C) Far away from the inductive load
    (D) Any where

7. Inductance of a coil Varies
    (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)

8. Power factor of the following circuit will be unity
    (A) Inductance
    (B) Capacitance
    (C) Resistance
    (D) Both (A) and (B)

9. The r.m.s. value of alternating current is given by steady (D.C.) current which when flowing through a given circuit for a given time produces
    (A) The more heat than produced by A.C. when flowing through the same circuit
    (B) The same heat as produced by A.C. when flowing through the same circuit
    (C) The less heat than produced by A.C. flowing through the same circuit
    (D) None of the above

10. In a pure resistive circuit
    (A) Current lags behind the voltage by 90°
    (B) Current leads the voltage by 90°
    (C) Current can lead or lag the voltage by 90°
    (D) Current is in phase with the voltage

11. Time constant of a circuit is the time in seconds taken after the application of voltage to each
    (A) 25% of maximum value
    (B) 50% of maximum value
    (C) 63% of maximum value
    (D) 90% of the maximum value

12. 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?
    (A) 0°
    (B) 45°
    (C) 90°
    (D) 180°

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