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Physics Alternating Current Online Mcqs Test

Mustansar KhanLast Updated: October 13, 2025

Important Physics Alternating Current Question and Answer

Total Questions:	49
Time Allowed:	25 Minutes
Total Marks:	49
How to Attempt Test:	Please choose the right Option in MCQ-type question.
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Physics Alternating Current Practice Test Online With Explanation

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1. Which of the following devices can cause a phase lead in an AC circuit?

Resistor

Transformer

Capacitor

Inductor

2. What is the purpose of phase analysis in AC circuits?

To understand power distribution

To calculate resistance

To measure current

To measure voltage

3. What is the frequency of AC used in the United States?

100 Hz

50 Hz

60 Hz

25 Hz

4. Which of these quantities is the same for all types of EM waves in a vacuum?

Frequency

Energy

Wavelength

Speed

5. Which of the following AC circuit components stores energy in an electric field?

Capacitor

Resistor

Inductor

Transformer

6. Which electromagnetic wave is used in satellite communication?

X-rays

Gamma rays

Microwaves

Infrared rays

7. Which wave in the EM spectrum is used for medical imaging?

Radio waves

Gamma rays

Infrared

X-rays

8. Which component in an AC circuit causes energy to be dissipated as heat?

Inductor

Transformer

Capacitor

Resistor

9. What is the result of applying AC through a pure resistor?

Current leads voltage

Current is zero

Voltage and current are in phase

Voltage leads current

10. When AC passes through a capacitor, it:

Passes with phase lead

Reverses direction

Passes with phase lag

Is blocked completely

11. Which EM wave has a frequency just above visible light?

Infrared

Ultraviolet

X-rays

Radio waves

12. What happens to the power factor in a purely inductive or capacitive circuit?

It remains unchanged

It becomes 1

It becomes negative

It becomes zero

13. The term “rms value” in AC stands for:

Radiant mechanical signal

Root mean square

Resistance maximum supply

Radio mean speed

14. Which of the following AC circuit components stores energy in a magnetic field?

Diode

Inductor

Resistor

Capacitor

15. Which of the following is true in a capacitive AC circuit?

Voltage lags current by 180°

Voltage leads current

Voltage and current are in phase

Current leads voltage

16. Which electromagnetic wave is responsible for sunburn?

Gamma rays

X-rays

Ultraviolet rays

Microwaves

17. In which component of an AC circuit does the current lead the voltage by 90°?

Inductor

Transformer

Resistor

Capacitor

18. What is the phase difference in an AC circuit with only a capacitor?

Voltage lags current by 90°

No phase difference

Voltage leads current by 90°

Voltage leads current by 180°

19. Which EM wave is used in remote controls?

X-rays

Radio waves

Gamma rays

Infrared rays

20. What is the significance of phase angle in an AC circuit?

Determines speed

Shows the strength of the current

Determines direction

Shows the time difference between voltage and current

21. Which part of the EM spectrum is used for cooking in microwave ovens?

Infrared

Microwaves

Radio waves

Ultraviolet

22. Which property is different among the different waves in the EM spectrum?

Frequency

Medium

Direction

Speed

23. What is meant by 'phase lag' in AC circuits?

Voltage is ahead of current

Both occur simultaneously

Voltage and current are in phase

Current is ahead of voltage

24. Which of the following waves has the highest energy?

Infrared

Visible light

Radio waves

Gamma rays

25. Which property of AC allows it to be transmitted over long distances efficiently?

Ability to reverse direction

Constant voltage

Can be converted to DC

Can be stepped up or down using transformers

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26. The EM wave with the shortest wavelength is:

Microwaves

Ultraviolet

Gamma rays

X-rays

27. In an inductor-only AC circuit, the voltage:

Lags current by 90°

Is in phase with current

Leads current by 180°

Leads current by 90°

28. Which electromagnetic wave is used in sterilizing surgical instruments?

Ultraviolet rays

Microwaves

Radio waves

Infrared rays

29. Which electromagnetic wave has more penetrating power?

Infrared

Gamma rays

X-rays

Ultraviolet

30. In which case is the power factor of an AC circuit maximum?

RC circuit

Pure resistor

Pure inductor

Pure capacitor

31. Which EM wave is used in night vision equipment?

Ultraviolet

Microwaves

Infrared

Gamma rays

32. What is the unit of reactance in an AC circuit?

Henry

Ampere

Volt

Ohm

33. What is the waveform of typical alternating current?

Triangular wave

Constant wave

Square wave

Sine wave

34. How does increasing the frequency affect capacitive reactance?

Becomes zero

Decreases it

Increases it

No effect

35. What is the result of the vector addition of current and voltage in an RLC circuit?

Phase angle

Power factor

Impedance

Reactance

36. Which EM wave is used in radar systems?

Radio waves

X-rays

Microwaves

Infrared

37. Which EM wave is used in cancer treatment?

Microwaves

Gamma rays

Ultraviolet

Infrared

38. Which wave has more energy than UV but less than gamma rays?

X-rays

Microwaves

Radio waves

Infrared

39. What determines the impedance of an RLC circuit?

Resistance, inductance, and capacitance

Only inductance

Only resistance

Resistance and capacitance

40. What happens to current in an inductive AC circuit?

Leads voltage

Is in phase

Is zero

Lags voltage

41. In an AC circuit with only a resistor, what is the phase difference between current and voltage?

45°

180°

90°

0°

42. In which part of the electromagnetic spectrum does visible light lie?

Between infrared and ultraviolet

Between ultraviolet and X-rays

Between X-rays and gamma rays

Between microwaves and radio waves

43. Which device is used to measure the frequency of AC?

Voltmeter

Wattmeter

Frequency meter

Ammeter

44. How does a capacitor behave in a DC circuit after a long time?

Acts as a conductor

Increases current

Acts as an insulator

Discharges quickly

45. What happens when a capacitor is connected to an AC source?

It blocks current

It acts like a resistor

It charges fully

It allows current with a phase lead

46. What is the phase relationship between current and voltage in an inductive AC circuit?

Voltage leads current

Current leads voltage

Voltage lags current

Voltage and current are in phase

47. Which EM wave is used in mobile communication?

Gamma rays

Microwaves

Infrared

X-rays

48. What causes phase difference in AC circuits?

Inductance and capacitance

Voltage drop

Resistance only

Only capacitance

49. Which of the following is not part of the electromagnetic spectrum?

Microwaves

X-rays

Sound waves

Infrared

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Mustansar KhanLast Updated: October 13, 2025

Physics Alternating Current Online Mcqs Test

Important Physics Alternating Current Question and Answer

Physics Alternating Current Practice Test Online With Explanation

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