Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 70 of 494
An AC voltage described by the equation \( v(t) = 170 \sin(120\pi t)\text{ V} \) is applied across a full-wave bridge rectifier. What is the fundamental ripple frequency of the rectified output?
A
\( 60\text{ Hz} \)
B
\( 120\text{ Hz} \)
C
\( 240\text{ Hz} \)
D
\( 30\text{ Hz} \)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: \( 120\text{ Hz} \)
Concept:

The input angular frequency \( \omega = 2\pi f \) determines the input frequency, which doubles at the output of a full-wave rectifier.

Formula:

$$\omega = 2\pi f_{\text{in}} \implies f_{\text{in}} = \frac{\omega}{2\pi}$$
$$f_{\text{ripple}} = 2 f_{\text{in}}$$

Solution:

  • From the given equation, \( \omega = 120\pi\text{ rad/s} \).


  • $$f_{\text{in}} = \frac{120\pi}{2\pi} = 60\text{ Hz}$$


  • For full-wave rectification:


  • $$f_{\text{ripple}} = 2 \times 60\text{ Hz} = 120\text{ Hz}$$


Why other options are incorrect:

  • Option A: \( 60\text{ Hz} \) is the input frequency (and the ripple frequency for a half-wave rectifier).


  • Option C: Quadrupling the input frequency is incorrect for a standard single-phase full-wave rectifier.


  • Option D: Frequency is not halved.

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