Free Alternating Current MCQs with Answers
592 Alternating Current MCQs from Physics, each with the correct answer and a written explanation of why it is correct. Free and unlimited, with no account needed.
Alternating current varies periodically, so phase relationships become essential when current passes through a resistor, capacitor or inductor. The chapter distinguishes resistance from capacitive and inductive reactance, explains phase lead and lag, and connects changing electric and magnetic fields with the production and properties of electromagnetic waves.
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Read the Alternating Current notesFree MDCAT chapter notes with key terms592 questions · page 14 of 30
- A. Resistance and inductance
- B. Resistance and reactance
- C. Inductance and capacitance
- D. None of these
Explanation: Impedance in an AC circuit is the combined effect of resistance (which opposes the flow of current) and reactance (which accounts for the…
Correct answer: Resistance and reactance- A. Farad
- B. Henry
- C. Tesla
- D. Ohm
Explanation: The correct option, ohm (Ω), is the unit of impedance, representing the opposition to the flow of alternating current in a circuit.
Correct answer: Ohm- A. Combined effect of resistance and reactance
- B. Another name of resistance
- C. Another name of inductance and capacitance
- D. None of these
Explanation: In an RLC circuit, impedance represents the combined effect of resistance and reactance, which includes the opposition to the flow of…
Correct answer: Combined effect of resistance and reactance- A. Irms cos θ
- B. Irms sin θ
- C. Io cosθ
- D. Infinity
Explanation: The correct option is (Irms), which stands for the root mean square current.
Correct answer: Irms cos θ- A. tan curve
- B. Curved line
- C. Sine curve
- D. Straight line
Explanation: The correct option, "sin curve," represents the standard graphical representation of the relationship between time and voltage in an AC…
Correct answer: Sine curve- A. A.C is virtual
- B. Average current for complete cycle is zero
- C. A.C cannot pass through D.C ammeter
- D. None of the above
Explanation: In an AC circuit, the current changes direction periodically, resulting in positive and negative values that cancel each other out over a…
Correct answer: Average current for complete cycle is zero- A. Peak value
- B. Minimum value
- C. Average value
- D. Zero value
Explanation: The correct option, "peak value," represents the highest magnitude reached by the voltage or current waveform in one cycle.
Correct answer: Peak value- A. Ohm
- B. Ampere
- C. Volt
- D. None of the above
Explanation: Explanation is provided in the picture below.
Correct answer: Ohm- A. + ve direction of A.C
- B. - ve direction of A.C
- C. Towards zero
- D. None of the above
Explanation: Explanation is provided in the picture below..
Correct answer: + ve direction of A.C- A. - ve direction of A.C
- B. + ve direction of AC
- C. Towards zero
- D. All of the above
Explanation: Explanation is provided in the picture below.
Correct answer: - ve direction of A.C- A. Cell
- B. A.C generator
- C. A.C transformer
- D. Motor
Explanation: The correct option, "AC generator (alternator)," refers to a device that converts mechanical energy into alternating current (AC)…
Correct answer: A.C generator- A. Impedance
- B. Inductance
- C. Resistance
- D. None of the above
Explanation: The correct option, "Impedance," refers to the overall opposition to the flow of current in an AC circuit, combining both resistance and…
Correct answer: Impedance- A. In phase with emf
- B. The emf by 90o
- C. Leads the emf by 90'
- D. All of the above
Explanation: In a purely capacitive AC circuit, the current lags behind the electromotive force (emf) by 90 degrees.
Correct answer: Leads the emf by 90'- A. Remain unchanged
- B. Increases
- C. Decreases
- D. None of the above
Explanation: With high frequencies, capacitive reactance decreases.
Correct answer: Decreases- A. Decreases
- B. Increases as square of frequency
- C. Remain unchanged
- D. Increases as directly to frequency
Explanation: The correct option, "Increases as directly to frequency," means that as the frequency of an AC supply increases, the inductive reactance…
Correct answer: Increases as directly to frequency- A. A
- B. B
- C. C
- D. D
Explanation: Explanation is provided in the picture below.
Correct answer: C- A. Decrease
- B. Increases
- C. Remains constant
- D. First decrease, becomes minimum and then increase
Explanation: The correct option, "First decrease, becomes minimum and then increase," describes the behavior of impedance in an LCR series circuit as…
Correct answer: First decrease, becomes minimum and then increase- A. Hertz
- B. Henry
- C. Volt
- D. Ohm
Explanation: The correct option, "ohm (Ω)," represents the unit of impedance. Impedance is the total opposition that a circuit offers to the flow of…
Correct answer: Ohm- A. A
- B. B
- C. C
- D. D
Explanation: explanation is provided in the picture below.
Correct answer: C- A. A
- B. B
- C. C
- D. D
Explanation: Explanation is provided in the picture below.
Correct answer: C