Physics Electrostatics ETEA 2016
PMDC Verified Question 119 of 131
Q.90 A charged capacitor stores 10C at 40V. Its stored energy is:
A
400J
B
4J
C
0.2 J
D
200 J
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option D: 200 J
1. Concept:

The potential energy stored in a charged capacitor can be found directly if the total charge and potential difference are known.

2. Formula:

$$ U = \frac{1}{2} Q V $$

3. Solution:

  • Given charge: \( Q = 10 \text{ C} \).


  • Given potential difference: \( V = 40 \text{ V} \).


  • Calculate: \( U = \frac{1}{2} (10) (40) \)


  • Result: \( U = 5 \times 40 = 200 \text{ J} \).


4. Why other options are incorrect:

Option A comes from using \( U = Q \times V \), which omits the vital \( \frac{1}{2} \) factor representing the average voltage during the charging process.

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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