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 13 of 30
- A. In phase
- B. Out of phase
- C. Lead each other
- D. None of these
Explanation: In a resistive AC circuit, the correct option "in phase" means that the instantaneous values of voltage and current reach their maximum…
Correct answer: In phase- A. R/L
- B. L/R
- C. RL
- D. None of these
Explanation: The correct option, "None of these," is chosen because none of the provided options accurately match the dimensions of RC, Dimensionsare…
Correct answer: None of these- A. 450 Hz
- B. 512 Hz
- C. 1 KHz
- D. 159 Hz
Explanation: The impedance ((Z)) of an inductor ((L)) and a capacitor ((C)) in series is given by the formula:For impendance to be same XL and Xc Must…
Correct answer: 159 Hz- A. 1A
- B. 0.1 A
- C. 11 A
- D. 10 A
Explanation: The turns ratio (N2/N1) of a transformer is the ratio of the number of turns in the secondary coil (N2) to the number of turns in the…
Correct answer: 10 A- A. Parallel to each other
- B. Perpendicular to each other
- C. Such that V leads I
- D. None of these
Explanation: The correct option ("parallel to each other") means that in a resistive circuit, the voltage and current vectors are in phase and have the…
Correct answer: Such that V leads I- A. P = VI sin θ
- B. P =12R
- C. P = VR
- D. P= VI cos θ
Explanation: When voltage (V) and current (I) are in phase, the power (P) is expressed as the product of the voltage and current magnitudes multiplied…
Correct answer: P= VI cos θ- A. Voltage V lags behind current I
- B. Current I leads the voltage
- C. Voltage leads the current I
- D. Both (a) and (b)
Explanation: The correct option ("Current I leads the voltage") indicates that in a capacitive circuit, the current reaches its maximum value before…
Correct answer: Current I leads the voltage- A. Reactance
- B. Resistance
- C. Impedance
- D. Capacitance
Explanation: The correct option is **Reactance**. Reactance specifically refers to the opposition offered by a capacitor to the flow of AC in a…
Correct answer: Reactance- A. Electrical energy
- B. Light energy
- C. Magnetic energy
- D. Heat energy
Explanation: The correct option is **magnetic energy**. In an inductance coil, energy is stored in the form of a magnetic field surrounding the coil.
Correct answer: Magnetic energy- A. Vrms/Irms
- B. Vrms x Irms
- C. Irms/Vrms
- D. Vmax x Vrms
Explanation: The correct option, Vrms/Irms, represents the ratio of the root mean square (rms) voltage to the root mean square (rms) current.
Correct answer: Vrms/Irms- A. Farad
- B. Ohm
- C. Newton
- D. All of these
Explanation: The correct option is Ohm. Reactance, specifically capacitive reactance, is measured in ohms for a capacitor.
Correct answer: Ohm- A. Inductance of the coil
- B. Capacitance of the coil
- C. Thickness of the coil
- D. None of these
Explanation: The reactance of a coil, also known as inductive reactance, depends directly on the inductance of the coil.
Correct answer: Inductance of the coil- A. Smaller than back emf
- B. Greater than back emf
- C. Equal to back emf
- D. None of these
Explanation: When an alternating voltage is applied to an inductor, it induces a changing magnetic field, which in turn generates a back electromotive…
Correct answer: Greater than back emf- A. Voltage V leads current I by 90o
- B. Voltage V leads current I by 270o
- C. Voltage V leads current I by 0o
- D. None of these
Explanation: In an AC circuit containing an inductor, the voltage across the inductor leads the current through the inductor by 90 degrees.
Correct answer: Voltage V leads current I by 90o- A. A
- B. B
- C. C
- D. D
Explanation: The phase diagram for an inductor in an AC circuit typically shows the relationship between voltage (V) and current (I) as a vector…
Correct answer: D- A. A
- B. B
- C. C
- D. D
Explanation: The phase diagram for a capacitor in an AC circuit typically shows the relationship between voltage (V) and current (I) as a vector…
Correct answer: C- A. milli ohm
- B. kilo ohm
- C. ohm
- D. none of these
Explanation: The correct unit for inductive reactance ( XL) when frequency ( f ) is in Hertz (Hz) and inductance (L) is in milli henry (mH) is ohms.
Correct answer: ohm- A. Mega ohm
- B. Milli ohm
- C. μ ohm
- D. None of these
Explanation: Explanation is provided in picture below
Correct answer: None of these- A. Electric motor
- B. Generator
- C. Turbine
- D. Transformer
Explanation: Generators convert mechanical energy into electrical energy, producing alternating current (AC) through electromagnetic induction.
Correct answer: Generator- A. The current depends upon the components connected in circuit
- B. The current lags the voltage by a phase angle of 90o
- C. The current leads the voltage by a phase angle of 90o
- D. The current and voltage are in same phase
Explanation: The correct option is C. The current leads the voltage by a phase angle of 90°.This statement describes the behavior of a purely…
Correct answer: The current leads the voltage by a phase angle of 90o