Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 130 of 494
In a bridge rectifier circuit, how do the four diodes conduct current throughout one full AC cycle?
A
All four diodes conduct continuously throughout both half-cycles
B
Diodes conduct in diagonal pairs: two during the positive half-cycle, and the other two during the negative half-cycle
C
Only one single diode conducts while the other three stay reverse-biased
D
Three diodes conduct simultaneously during each half-cycle
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: Diodes conduct in diagonal pairs: two during the positive half-cycle, and the other two during the negative half-cycle
Concept:

A full-wave bridge rectifier uses four diodes arranged in a bridge. Diagonal pairs alternate conduction on opposite half-cycles to direct load current in a single direction.

Formula:

$$\text{Positive Half-Cycle: } D_1, D_3 \text{ ON} \quad | \quad \text{Negative Half-Cycle: } D_2, D_4 \text{ ON}$$

Solution:

  • During the positive half-cycle, diodes \( D_1 \) and \( D_3 \) are forward-biased and conduct in series with the load.


  • During the negative half-cycle, diodes \( D_2 \) and \( D_4 \) are forward-biased and conduct through the load in the same direction.


  • This ensures continuous, unidirectional current across both half-cycles.


Why other options are incorrect:

  • Option A: Simultaneous conduction of all four diodes would short-circuit the AC secondary winding.
  • Option C: A single conducting diode produces half-wave rectification, not bridge rectification.
  • Option D: Three conducting diodes would short-circuit the AC source.

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