Quiz  /  Alternating Current and Voltage Class 12 MCQ Questions With...

  • 1. 
    Average power dissipated in an ideal inductor in a.c. circuit is:

  • Infinite
  • 100
  • 0
  • 1

  • 2. 
    What does RC stand for?

  • Remote Control
  • Radio Control
  • Resistor Capacitor
  • Rotary Club

  • 3. 
    Which is the correct equation of  VrmsV_{rms}Vrms​ ?

  • Vrms=VoV_{rms}=V_oVrms​=Vo​
  • Vrms=2VoV_{rms}=\frac{\sqrt{2}}{V_o}Vrms​=Vo​2​​
  • Vrms=Vo2V_{rms}=\frac{V_o}{\sqrt{2}}Vrms​=2​Vo​​
  • Vrms=Vo2sin⁡ 2tV_{rms}=\frac{V_o}{\sqrt{2}}\sin\ 2tVrms​=2​Vo​​sin 2t

  • 4. 
    If the frequency of the AC voltage across an inductor is doubled, the inductive reactance of that inductor

  • increases to 4 times its original value.
  • increases to twice its original value.
  • decreases to one-half its original value.
  • decreases to one-fourth its original value.

  • 5. 
    An electrical element X when connected to an alternating voltage source has current through it leading the voltage by 2radian. Identify X

  • Capacitor
  • Resistor
  • Inductor
  • Series LR circuit

  • 6. 
    All of the following have the same units except:

  • inductance.
  • capacitive reactance.
  • impedance.
  • resistance.

  • 7. 
    A resistor is connected to an AC power supply. On this circuit, the current

  • leads the voltage by 90°.
  • lags the voltage by 90°.
  • is in phase with the voltage.
  • none of the given answers

  • 8. 
    Rms value of ac current is the equivalent direct current which produces

  • the same average energy
  • the same power dissipation
  • the same rate of current flow
  • the same rate of power use

  • 9. 
    What is the Peak voltage of the signal shown on the multimeter?

  • 1000 V
  • 1414 V
  • 1500 V
  • 707 V

  • 10. 
    A pure capacitor is connected to an AC power supply. In this circuit, the current

  • leads the voltage by 90°.
  • lags the voltage by 90°.
  • is in phase with the voltage.
  • none of the given answers

  • 11. 
    An electric current that continually reverses direction over time is known as a(n)

  • direct current
  • alternating current
  • simple current

  • 12. 
    In a circuit containing resistance only, the voltage and current are ____________________ with oneanother.

  • together
  • anti phase
  • in phase
  • full rotation

  • 13. 
    The power factor is the ratio of __________________ power to _________________ power.

  • true and apparent
  • true and real
  • positive and negative
  • factor and real

  • 14. 
    A capacitor 120 µF is connected to an AC source of 6 V with frequency 100 Hz. If the frequency is increased to 200 Hz, the reactance of the capacitor will be

  • half the original value.
  • same as the original value.
  • two times the original value.
  • the reciprocal of the original value.

  • 15. 
    A sine wave has a peak value of 354 V, What is the RMS value?

  • 250 V
  • 500 V
  • 354 V
  • 200V

  • 16. 
    A power supply has a peak value of 433 Volts sine wave, what is the effective dc voltage of this power supply?

  • 306 V
  • 433 V
  • 612 V
  • 220 V

  • 17. 
    The function of a generator is to change ____.

  • mechanical energy to electrical energy
  • electrical energy to mechanical energy
  • electrical energy to chemical energy
  • chemical energy to electrical energy

  • 18. 
    The current in an inductive circuit _____.

  • is faster than the voltage
  • is the same as the voltage
  • lags the voltage
  • counteracts the voltage

  • 19. 
    What words are missing from the following statement? The impedance of a series RCL circuit at resonance will be _______ and equal to the circuit _______ .

  • Minimum and resistance.
  • Maximum and resistance.
  • Minimum and reactance.
  • Maximum and reactance

  • 20. 
    An A.C source is connected to a resistive circuit. Which of the following is true ?

  • Current leads the voltage and both are in same phase
  • Current lags behind the voltage and both are in same phase
  • Current and voltage are in same phase
  • Any of the above may be true depending upon the value of resistance

  • 21. 
    The highest value reached by the voltage or current in one cycle is called:

  • Instantaneous value
  • Peak to peak value
  • Peak value
  • Root mean square value

  • 22. 
    A pure inductor is connected to an a.c. source of frequency 100 Hz and the r.m.s. value of the voltage is 12 V. If the peak value of the current flowing through the inductor is 14 A, what is the inductance of the inductor?

  • 1.6 mH
  • 1.9 mH
  • 30 mH
  • 39 mH

  • 23. 
    A heater is rated as 230 V, 10 kW. The value 230 V refers to

  • average voltage
  • r.m.s voltage
  • peak voltage

  • 24. 
    A pure inductor of inductance 15 H is connected to an a.c.s source of frequency 100 Hz. If the r.m.s. value of the voltage is 12 V, what is the maximum instantaneous output power?

  • 1.3 ×10−3W\times10^{-3}W×10−3W
  • 1.5 ×10−2W\times10^{-2}W×10−2W
  • 0 W
  • 1.5 W
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