Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 180 of 494
In a bridge full-wave rectifier, which pairs of diodes conduct current during the negative half-cycle of the AC input voltage?
A
Diodes D2 and D4 (the alternate diagonal pair)
B
Diodes D1 and D3 only
C
Diodes D1 and D4 only
D
No diodes conduct
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: Diodes D2 and D4 (the alternate diagonal pair)
Concept:

During the negative half-cycle, the polarity of the AC input reverses, forward-biasing the alternate diagonal pair of diodes (\( D_2 \) and \( D_4 \)) to maintain unidirectional current through the load.

Formula:

$$\text{Negative Half-Cycle: } D_2, D_4 \text{ (Forward Biased, ON)} \quad \text{and} \quad D_1, D_3 \text{ (Reverse Biased, OFF)}$$

Solution:

  • The bottom secondary terminal becomes positive relative to the top terminal.


  • This forward-biases diodes \( D_2 \) and \( D_4 \), directing current through the load in the same direction as during the positive half-cycle.


  • Diodes \( D_1 \) and \( D_3 \) are reverse-biased and block current.


Why other options are incorrect:

  • Option B: Diodes \( D_1 \) and \( D_3 \) conduct during the positive half-cycle.
  • Option C: \( D_1 \) and \( D_4 \) are in different branches and do not conduct as a pair.
  • Option D: In full-wave rectification, conduction occurs during both half-cycles.

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