# Electronic Devices and Circuits Questions and Answers – Bridge Rectifier

This set of Electronic Devices and Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Bridge Rectifier”.

1. DC average current of a bridge full wave rectifier (where Im is the maximum peak current of input).
a) 2Im
b) Im
c) Im/2
d) 1.414Im

Explanation: Average DC current of half wave rectifier is Im. Since output of half wave rectifier contains only one half of the input. The average value is the half of the area of one half cycle of sine wave with peak Im. This is equal to Im.

2. DC power output of bridge full wave rectifier is equal to (Im is the peak current and RL is the load resistance).
a) 2 Im2RL
b) 4 Im2RL
c) Im2RL
d) Im2 RL/2

Explanation: DC output power is the power output of the rectifier. We know VDC for a bridge rectifier is 2Vm and IDC for a bridge rectifier is 2Im. We also know VDC=IDC/RL. Hence output power is 4Im2RL.

3. Ripple factor of bridge full wave rectifier is?
a) 1.414
b) 1.212
c) 0.482
d) 1.321

Explanation: Ripple factor of a rectifier measures the ripples or AC content in the output. It’s obtained by dividing AC rms output with DC output. For full wave bridge rectifier it is 0.482.

4. If input frequency is 50Hz then ripple frequency of bridge full wave rectifier will be equal to_________
a) 200Hz
b) 50Hz
c) 45Hz
d) 100Hz

Explanation: Since in the output of bridge rectifier one half cycle is repeated, the frequency will be twice as that of input frequency. So, f=100Hz.

5. Transformer utilization factor of bridge full wave rectifier _________
a) 0.623
b) 0.812
c) 0.693
d) 0.825

Explanation: Transformer utilization factor is the ratio of AC power delivered to load to the DC power rating. This factor indicates effectiveness of transformer usage by rectifier. For bridge full wave rectifier it’s equal to 0.693.
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6. If peak voltage on a bridge full wave rectifier circuit is 5V and diode cut in voltage os 0.7, then the peak inverse voltage on diode will be_________
a) 4.3V
b) 9.3V
c) 8.6V
d) 3.6V

Explanation: PIV is the maximum reverse bias voltage that can be appeared across a diode in the circuit. If PIV rating of diode is less than this value breakdown of diode may occur.. Therefore, PIV rating of diode should be greater than PIV in the circuit, For bridge rectifier PIV is Vm-VD = 5-1.4=3.6.

7. Efficiency of bridge full wave rectifier is_________
a) 81.2%
b) 50%
c) 40.6%
d) 45.33%

Explanation: It’s obtained by taking ratio of DC power output to maximum AC power delivered to load. Efficiency of a rectifier is the effectiveness of rectifier to convert AC to DC. It’s usually expressed inn percentage. For bridge full wave rectifier, it’s 81.2%.

8. In a bridge full wave rectifier, the input sine wave is 40sin100t. The average output voltage is_________
a) 22.73V
b) 16.93V
c) 25.47V
d) 33.23V

Explanation: The equation of sine wave is in the form Emsinωt.
Therefore, Em=40. Hence output voltage is 2Em=80V.

9. Number of diodes used in a full wave bridge rectifier is_________
a) 1
b) 2
c) 3
d) 4

Explanation: The model of a bridge rectifier is same as Wein Bridge. It needs 4 resistors. Bridge rectifier needs 4 diodes while centre tap configuration requires only one.

10. In a bridge full wave rectifier, the input sine wave is 250sin100t. The output ripple frequency will be_________
a) 50Hz
b) 200Hz
c) 100Hz
d) 25Hz

Explanation: The equation of sine wave is in the form of Emsinωt. So, ω=100 and frequency (f)=ω/2=50Hz. Since output of bridge rectifier have double the frequency of input, f=100Hz.

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