Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 260 of 494
A half-wave rectifier operating at line frequency \( f = 50\text{ Hz} \) delivers a DC current of \( I_{\text{dc}} = 100\text{ mA} \) to a load. What filter capacitance \( C \) is required to maintain the peak-to-peak ripple voltage below \( 2.0\text{ V} \)?
A
1000 µF
B
500 µF
C
100 µF
D
250 µF
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option A: 1000 µF
Concept:

For a half-wave rectifier with a shunt capacitor filter, the peak-to-peak ripple voltage is related to the DC load current, line frequency, and capacitance by \( V_r = \frac{I_{\text{dc}}}{f C} \).

Formula:

$$V_r = \frac{I_{\text{dc}}}{f C} \implies C = \frac{I_{\text{dc}}}{f \cdot V_r}$$

Solution:

  • Given: \( I_{\text{dc}} = 100\text{ mA} = 0.10\text{ A} \), \( f = 50\text{ Hz} \), and \( V_r = 2.0\text{ V} \).


  • Required capacitance: \( C = \frac{0.10\text{ A}}{50\text{ Hz} \times 2.0\text{ V}} = \frac{0.10}{100} = 0.0010\text{ F} = 1000\ \mu\text{F} \).


Why other options are incorrect:

  • Option B: 500 µF is the capacitance required for a full-wave rectifier (where ripple frequency is \( 2f \)).
  • Option C: 100 µF would result in a large ripple voltage of 20 V.
  • Option D: 250 µF would produce a ripple voltage of 8 V.

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