Physics Electrostatics MDCAT 2012
PMDC Verified Question 126 of 131
Q.83 What will be the effect on the capacitance of a capacitor if area of each plate is doubled with separation between the plates is halved?
A
Capacitance remains same
B
Capacitance becomes double
C
Capacitance becomes four times
D
Capacitance reduces of half
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: Capacitance becomes four times
1. Concept:

The capacitance of a parallel plate capacitor is directly proportional to the area of its plates and inversely proportional to the distance separating them.

2. Formula:

$$ C = \frac{\epsilon_0 A}{d} $$

3. Solution:

  • Given changes: New area \( A' = 2A \) and new distance \( d' = d / 2 \).


  • Substitute into the formula: \( C' = \frac{\epsilon_0 (2A)}{d/2} \)


  • Simplify: \( C' = \frac{2 \epsilon_0 A}{d/2} = 4 \left( \frac{\epsilon_0 A}{d} \right) = 4C \)


4. Why other options are incorrect:

Option B would occur if only the area was doubled OR if only the separation was halved. By combining both effects, they multiply (\( 2 \times 2 = 4 \)).

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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