Physics Electronics PMDC Conceptual Practice
PMDC Verified Question 182 of 494
What is the theoretical Form Factor (\( \text{FF} = V_{\text{rms}} / V_{\text{dc}} \)) of a full-wave rectified sinusoidal waveform?
A
1.57
B
0.482
C
1.11 (π / (2√2))
D
1.21
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: 1.11 (π / (2√2))
Concept:

Form Factor (\( \text{FF} \)) is the ratio of the RMS value to the average DC value of a rectified waveform.

Formula:

$$\text{FF}_{\text{full-wave}} = \frac{V_{\text{rms}}}{V_{\text{dc}}} = \frac{V_m / \sqrt{2}}{2 V_m / \pi} = \frac{\pi}{2\sqrt{2}} \approx 1.1107$$

Solution:

  • For a full-wave rectifier, \( V_{\text{rms}} = \frac{V_m}{\sqrt{2}} \) and \( V_{\text{dc}} = \frac{2V_m}{\pi} \).


  • Calculating the ratio: \( \text{FF} = \frac{\pi}{2\sqrt{2}} = \frac{3.1416}{2.8284} \approx 1.11 \).


Why other options are incorrect:

  • Option A: 1.57 is the Form Factor of a half-wave rectifier (\( \pi / 2 \)).
  • Option B: 0.482 is the ripple factor of a full-wave rectifier.
  • Option D: 1.21 is the ripple factor of a half-wave rectifier.

Quality & Fidelity Assurance: Every question on BeambePrep is rigorously curated against the official PMDC syllabus with zero filler, zero out-of-syllabus content, and zero typos. When an authentic past paper originally contained a historical mistake or ambiguity from the examining board (such as UHS or NUMS), BeambePrep faithfully reflects the original paper while detailing the nuance and scientific consensus in the autopsy above.

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