Physics Current Electricity NUMS 2020
PMDC Verified Question 84 of 112
The power of an electric bulb is 100W. It is connected to 110V power is supply. The resistance of electric bulb will be?
A
11 \(\Omega\)
B
121 \(\Omega\)
C
20 \(\Omega\)
D
200 \(\Omega\)
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option B: 121 \(\Omega\)
Concept:

The power rating of a device is related to its internal resistance and the operating voltage.

Formula:

$$ P = \frac{V^2}{R} \implies R = \frac{V^2}{P} $$

Solution:

  • Given Voltage \( V = 110 \text{ V} \).


  • Power \( P = 100 \text{ W} \).


  • \( R = \frac{(110)^2}{100} = \frac{12100}{100} = 121 \, \Omega \).


Why other options are incorrect:

  • Opt A: This is \( V/P \), which is meaningless dimensionally.


  • Opt C, D: Mathematical errors.

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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