Free Alternating Current MCQs with Answers

• A. Tranverse
• B. Electromagnetic
• C. Longitudinal
• D. Transverse and electromagnetic

Explanation: Microwaves are electromagnetic waves of wavelength ranging from 1 mm to 30 cm. Their frequencies range between 1,000 to 300,000 MHz.

• A. An electromagnetic wave
• B. Sound wave
• C. Longitudinal wave
• D. Standing wave

Explanation: Microwaves are a form of "electromagnetic" radiation; that is, they are waves of electrical and magnetic energy moving together through…

• A. 1
• B. 0
• C. -1
• D. 0.5

Explanation: This is the correct answer. In a resonant series circuit, the power factor is equal to 1, which represents a perfect or unity power…

• A. Increases
• B. Decreases
• C. Remains the same
• D. Becomes zero

Explanation: This is the correct answer. At higher frequencies, capacitive reactance decreases.

• A. 3525.0 volts
• B. 35.35 volts
• C. 353.5 volts
• D. 3.535 volts

Explanation: The correct answer is 353.5 volts. The A.C. voltmeter reads the RMS (Root Mean Square) value of the voltage, which is 250 volts in this…

• A. 180o
• B. 90o
• C. 0o
• D. None of these

Explanation: This is the correct answer. At resonance in a series RLC circuit, the phase angle between the current and voltage is 0 degrees.

• A. 9.4 kHz
• B. 940 kHz
• C. 94 kHz
• D. None of these

Explanation: This is the correct answer. When electrons in the transmitting antenna vibrate at a frequency of 94,000 times per second, the resulting…

• A. 100
• B. 0.707
• C. 70.7
• D. 50

Explanation: In alternating current (AC) circuits, the RMS (Root Mean Square) value is a measure of the effective value of the AC current or voltage.

• A. 2f
• B. 3f
• C. f
• D. 4f

Explanation: In alternating current (AC), the current and voltage follow a sinusoidal pattern.

• A. Direction of I
• B. Magnitude of I
• C. Nature of current
• D. None

Explanation: Dissipation of Heat in Electrical Circuits: Heat dissipation in an electrical circuit is primarily governed by Joule's Law, which states…

• A. Chemical effect
• B. Heating effect
• C. Magnetic effect
• D. None

Explanation: The question asks which effect of electric current does not depend on the direction of current (I).

• A. 1:2
• B. 2:1
• C. 1:1
• D. none

Explanation: In a resistive AC circuit, the voltage and current are sinusoidal and in phase.

• A. 100%
• B. 200%
• C. 50%
• D. No change

Explanation: In alternating current (AC) circuits, when the peak current is doubled, this results in a 100% increase in the peak current.

• A. 300%
• B. 200%
• C. 100%
• D. none

Explanation: In an electrical circuit, the power (P) is given by the formula P = Vpeak * Ipeak, where Vpeak is the peak voltage and Ipeak is the peak…

• A. 2 times
• B. 3 times
• C. 4 times
• D. none

Explanation: The correct answer is that the frequency of the output alternating current becomes 2 times if the frequency of the A.C.

• A. Zero
• B. Infinite
• C. Finite
• D. None

Explanation: An inductor is a passive electrical component that stores energy in a magnetic field when electric current flows through it.

• A. Doubles
• B. Quadrupled
• C. Tripled
• D. None

Explanation: In electrical circuits, the inductive reactance (XL) of an inductor is calculated using the formula XL = 2πfL, where f is the frequency…

• A. Constant inductance
• B. Decreasing inductance
• C. Increasing inductance
• D. None

Explanation: Inductive Reactance (XL): In an AC circuit, inductive reactance is the opposition offered by an inductor to the change of current…

• A. Low pass filter
• B. Medium part filter
• C. High pass filter
• D. None

Explanation: In electronics, a low pass filter is a circuit that allows signals with a frequency lower than a certain cutoff frequency to pass through…

• A. Current
• B. Voltage
• C. Resistance
• D. None

Explanation: In a capacitive circuit connected to DC, the capacitor initially allows current to pass as it charges up.