Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 190 of 494
A full-wave rectifier delivers \( 80.0\text{ W} \) of DC power to a load resistor while consuming \( 100.0\text{ W} \) of AC input power. What is its rectification efficiency, and how does it compare to the theoretical maximum for a half-wave rectifier?
A
40.0% (equal to a half-wave rectifier)
B
50.0% (lower than a half-wave rectifier)
C
80.0% (roughly double the maximum theoretical efficiency of a half-wave rectifier)
D
100.0% (ideal frictionless operation)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: 80.0% (roughly double the maximum theoretical efficiency of a half-wave rectifier)
Concept:

Rectification efficiency is the ratio of DC output power to AC input power: \( \eta = (P_{\text{dc}} / P_{\text{ac}}) \times 100\% \).

Formula:

$$\eta = \frac{P_{\text{dc}}}{P_{\text{ac}}} \times 100\%$$

$$\eta_{\text{max, full-wave}} \approx 81.2\% \quad \text{and} \quad \eta_{\text{max, half-wave}} \approx 40.6\%$$

Solution:

  • Given: \( P_{\text{dc}} = 80.0\text{ W} \) and \( P_{\text{ac}} = 100.0\text{ W} \).


  • Efficiency: \( \eta = \frac{80.0}{100.0} \times 100\% = 80.0\% \).


  • This is close to the theoretical maximum for full-wave rectifiers (\( 81.2\% \)) and roughly double that of half-wave rectifiers (\( 40.6\% \)).


Why other options are incorrect:

  • Option A: 40.0% is typical for half-wave rectifiers.
  • Option B: 50.0% underestimates the efficiency of this circuit.
  • Option D: 100.0% is physically impossible due to non-zero harmonic ripple and diode losses.

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