Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 270 of 494
If one of the four diodes in a full-wave bridge rectifier fails by becoming a permanent SHORT circuit, what will happen during normal circuit operation?
A
The transformer secondary winding will be directly short-circuited during the alternate half-cycle, likely blowing the fuse or destroying the other diodes
B
The circuit will convert into an ideal DC battery
C
The output efficiency will increase to 100%
D
The output ripple will drop to zero without a filter
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: The transformer secondary winding will be directly short-circuited during the alternate half-cycle, likely blowing the fuse or destroying the other diodes
Concept:

A shorted diode creates a zero-resistance path across one branch. When the opposite diode pair turns ON during the alternate half-cycle, it creates a direct short circuit across the transformer secondary winding.

Formula:

$$I_{\text{short}} = \frac{V_s}{R_{\text{winding}}} \to \text{Very Large Fault Current} \implies \text{Fuse Blows / Component Failure}$$

Solution:

  • On the half-cycle where the shorted diode's branch is active, current flows through the short.


  • On the alternate half-cycle, when another diode turns ON, the shorted diode creates a direct short circuit across the AC secondary winding.


  • This draws excessive fault current, blowing the protective fuse or destroying the remaining diodes and transformer.


Why other options are incorrect:

  • Option B: Short circuits cause overcurrent faults, not stable DC generation.
  • Option C: Efficiency drops to zero under a short-circuit fault condition.
  • Option D: Short-circuiting the source does not eliminate ripple.

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