Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 259 of 494
A full-wave bridge rectifier is fed by a transformer secondary with a peak voltage of \( V_m = 50.0\text{ V} \). If each silicon diode has a forward voltage drop of \( V_D = 0.70\text{ V} \), what is the peak voltage across the load resistor?
A
50.0 V
B
49.3 V
C
51.4 V
D
48.6 V
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 48.6 V
Concept:

In a bridge rectifier, two diodes conduct in series with the load during each half-cycle, introducing two forward voltage drops (\( 2 V_D \)).

Formula:

$$V_{\text{load,peak}} = V_m - 2 V_D$$

Solution:

  • Given: \( V_m = 50.0\text{ V} \) and \( V_D = 0.70\text{ V} \).


  • Total diode voltage drop: \( 2 \times 0.70\text{ V} = 1.40\text{ V} \).


  • Peak load voltage: \( V_{\text{load,peak}} = 50.0\text{ V} - 1.40\text{ V} = 48.60\text{ V} = 48.6\text{ V} \).


Why other options are incorrect:

  • Option A: 50.0 V assumes ideal diodes with zero forward voltage drop.
  • Option B: 49.3 V subtracts only one diode drop (\( 50.0 - 0.70 \)), as in a center-tapped rectifier.
  • Option C: 51.4 V incorrectly adds the diode drops to the supply voltage.

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