Physics Alternating Current PMDC Conceptual Practice
PMDC Verified Question 4 of 127
An alternating voltage \( V \) (in volts) is represented by the equation:

$$V = 300 \sin(100 \pi t)$$

What is the frequency \( f \) of this alternating voltage?
A
100 Hz
B
25 Hz
C
200 Hz
D
50 Hz
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 50 Hz
Concept:

Compare the given voltage equation to the standard equation for a sinusoidal alternating voltage.

Formula:

$$V = V_0 \sin(\omega t) = V_0 \sin(2\pi f t)$$

Solution:

Identify the angular frequency \( \omega \) from the equation:

$$\omega = 100 \pi\text{ rad/s}$$

Since \( \omega = 2 \pi f \), solve for frequency \( f \):

$$2 \pi f = 100 \pi$$

$$f = \frac{100 \pi}{2 \pi} = 50\text{ Hz}$$

Why other options are incorrect:

  • 100 Hz is the coefficient of \( \pi t \), which represents \( 2f \) instead of \( f \).

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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