Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 405 of 494
A center-tapped full-wave rectifier uses silicon diodes (\( V_B = 0.7\text{ V} \)). If the peak voltage from the center tap to either end of the secondary winding is \( 15.7\text{ V} \), what is the peak voltage across the load resistor?
A
\( 15.0\text{ V} \)
B
\( 14.3\text{ V} \)
C
\( 15.7\text{ V} \)
D
\( 30.0\text{ V} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: \( 15.0\text{ V} \)
Concept:

In a center-tapped rectifier, only one diode conducts in series with the load during each half-cycle, introducing a single forward drop \( V_B \).

Formula:

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

Solution:

  • The peak voltage per half-secondary is \( V_m = 15.7\text{ V} \).


  • A single diode conducts per half-cycle with a voltage drop of \( V_B = 0.7\text{ V} \).


  • Calculate peak load voltage:


  • $$V_{\text{load, peak}} = 15.7\text{ V} - 0.7\text{ V} = 15.0\text{ V}$$


Why other options are incorrect:

  • Option B: \( 14.3\text{ V} \) subtracts two diode drops (\( 1.4\text{ V} \)), which applies to bridge rectifiers.
  • Option C: \( 15.7\text{ V} \) neglects the forward barrier drop.
  • Option D: \( 30.0\text{ V} \) uses the total end-to-end secondary voltage rather than the voltage relative to the center tap.

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