Free Alternating Current MCQs with Answers

• A. 25
• B. 50
• C. 100
• D. 75

Explanation: Rectifiers produce unidirectional and pulsating voltage from A.C. source, the number of pulses per second in the rectified voltage remains…

• A. peak value
• B. peak to peak value
• C. cycle
• D. period

Explanation: Peak value is the maximum value obtained during one cycle so option A is correct.

• A. 4
• B. 3
• C. 2
• D. 5

Explanation: It is a fact that a bridge rectifier has 4 diodes. It is also called a full wave rectifier.

• A. Breakdown voltage
• B. Reverse voltage
• C. Forward voltage
• D. Knee voltage

Explanation: Knee voltage is the forward voltage at which the flow of the current through the PN junction of the diode increases rapidly.

• A. 100 Hz
• B. 25 Hz
• C. 200Hz
• D. 50Hz

Explanation: Frequency is unchanged i.e it remains 50 Hz.

• A. remains constant
• B. inverts for positive cycle
• C. changes for every cycle
• D. inverts for negative cycle

Explanation: Rectification changes alternate current to direct current where current remains positive throughout the cycle.

• A. 100 Hz
• B. 50 Hz
• C. 25 H
• D. 200 Hz

Explanation: Voltage = Maximum Voltage x sin (2πft) Therefore, 2f = 100 and frequency = 50 Hz

• A. Transformer
• B. Load resistance
• C. Power supply
• D. All of the above

Explanation: The half-wave rectifier is made up of an AC source, transformer (step-down), diode, and resistor (load).

• A. Full wave
• B. Half wave
• C. Both A and B
• D. None of them

Explanation: Lower the value of the ripple factor higher will be the efficiency of the rectifier.

• A. More
• B. Less
• C. Equal
• D. Zero

Explanation: A Step-Up Transformer is a power distribution transformer in which the secondary currents are higher than its primary voltage.

• A. 100 Hz
• B. 25 Hz
• C. 50 Hz
• D. 200 Hz

Explanation: In a full-wave rectifier, during each half cycle, the current flows through two diodes instead of just one.

• A. It needs a much smaller transformer for the same output.
• B. No center tap required.
• C. Less PIV rating per diode.
• D. All of the above options are correct.

Explanation: A bridge rectifier is preferred over an ordinary two diode full-wave rectifier because: The PIV is less per diode.

• A. 1.21
• B. 0.8
• C. 0.6
• D. 0.4

Explanation: Fact. As it is a fact, it should be memorized.

• A. Series
• B. Parallel
• C. Either series or parallel
• D. Neither series nor parallel

Explanation: Option A) Series and Option C) Either series or parallel are not correct because in a series connection, the 4uF capacitor will have a…

• A. Relative orientation
• B. Relative separation of two coils
• C. Reciprocity
• D. Permeability of the core material

Explanation: The mutual inductance of two coils is the property of their combination.

• A. 10 W
• B. 100 W
• C. 40 W
• D. Cannot be determined

Explanation: UsingVo = V sin(2𝜋ft) = 20 x sin (2𝜋 x 15 x 1/180) = 10 VUsingP = v2/ R = 102 / 10 = 10 W

• A. Power output = Power input
• B. Power output > Power input
• C. Power output ≥ Power input
• D. Power output < Power input

Explanation: The output power in a transformer is always less than the input power because of the different losses in a transformer.

• A. Very high
• B. Very low
• C. A few ohms
• D. Negative

Explanation: A half-wave rectifier converts an AC signal to DC by passing either the negative or positive half-cycle of the waveform and blocking the…

• A. Clamper
• B. Clipper
• C. Diode clamp
• D. Limiter

Explanation: A clamper is an electronic circuit that changes the DC level of a signal to the desired level without changing the shape of the applied…

• A. Smooth
• B. Pulsating
• C. Perfectly direct
• D. Alternating

Explanation: A rectifier is used to convert alternating current to pulsating direct current not smooth direct current.