Ac Fundamentals Circuits And Circuit Theory(Engineering > Electrical Engineering ) Questions and Answers

Question 1. The peak value of a sine wave is 200 V. Its average value is
  1.    127.4 V
  2.    141.4 V
  3.    282.8 V
  4.    200 V
Explanation:-
Answer: Option A. -> 127.4 V
Question 2. In a purely inductive circuit
  1.    Actual power is zero
  2.    Reactive power is zero
  3.    Apparent power is zero
  4.    None of above is zero
Explanation:-
Answer: Option A. -> Actual power is zero
Question 3. Time constant of a circuit is the time in seconds taken after the application of voltage to each
  1.    25% of maximum value
  2.    50% of maximum value
  3.    63% of maximum value
  4.    90% of the maximum value
Explanation:-
Answer: Option C. -> 63% of maximum value
Question 4. Magnitude of current at resonance in R-L-C circuit
  1.    Depends upon the magnitude of R
  2.    Depends upon the magnitude of L
  3.    Depends upon the magnitude of C
  4.    Depends upon the magnitude of R, Land C
Explanation:-
Answer: Option A. -> Depends upon the magnitude of R
Question 5. Inductance of a coil Varies
  1.    Directly as the cross-sectional area of magnetic core
  2.    Directly as square of number of turns
  3.    Inversely as the length of the iron path
  4.    As A to C
Explanation:-
Answer: Option D. -> As A to C
Question 6. Two waves of the same frequency have opposite phase when the phase angle between them is
  1.    360°
  2.    180°
  3.    90°
  4.    0°
Explanation:-
Answer: Option B. -> 180°
Question 7. When an alternating current passes through an ohmic resistance the electrical power converted into heat is
  1.    Apparent power
  2.    True power
  3.    Reactive power
  4.    None of the above
Explanation:-
Answer: Option B. -> True power
Question 8. The purpose of a parallel circuit resonance is to magnify
  1.    Current
  2.    Voltage
  3.    Power
  4.    Frequency
Explanation:-
Answer: Option B. -> Voltage
Question 9. An A.C. voltage is impressed across a pure resistance of 3.5 ohms in parallel with a pure inductance of impedance of 3.5 ohms,
  1.    The current through the resistance is more
  2.    The current through the resistance is less
  3.    Both resistance and inductance carry equal currents
  4.    None of the above
Explanation:-
Answer: Option C. -> Both resistance and inductance carry equal currents
Question 10. Form factor for a sine wave is
  1.    1.414
  2.    0.707
  3.    1.11
  4.    0.637
Explanation:-
Answer: Option C. -> 1.11
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