Physics Electrostatics ETEA 2023
PMDC Verified Question 48 of 131
Q.165 Two small charged objects attract each other with a force F when separated by a distance d. If the charge on each object is reduced to q/2 the force becomes:
A
F/16
B
F/8
C
F/4
D
F/2
Tap any option to test your recall and reveal the step-by-step Propolis autopsy.

Propolis Cognitive Error Autopsy

Official Correct Choice:
Option C: F/4
1. Concept:

The electrostatic force relies on the multiplied product of both interacting charges. Changing either charge individually affects the final total force.

2. Formula:

$$ F = k \frac{q_1 q_2}{d^2} $$

3. Solution:

  • Original force: \( F = k(q)(q)/d^2 \).


  • Both charges are individually halved, becoming \( q/2 \).


  • Substitute new charges: \( F' = k \frac{(q/2)(q/2)}{d^2} \).


  • Pull out the fractions: \( F' = \frac{1}{4} \left( k \frac{q_1 q_2}{d^2} \right) \).


  • The resulting force is exactly \( F/4 \).


4. Why other options are incorrect:

Option D occurs if only one of the charges is halved. Option A would occur if the distance was also accidentally doubled alongside the charge reductions.

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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