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CUET · PHYSICS · PYQ PAPER 2025

Three particles, each having a charge of \( 10 \, \mu\text{C} \), are placed at the vertices of an equilateral triangle of 10 mm. Find the work done by a person in pulling them apart to infinite separation.

  1. A 270 J
  2. B - 270 J
  3. C - 198 J
  4. D 4.5 J
Verified Solution

Answer & Solution

Correct Answer

(B) - 270 J

Step-by-step Solution

Detailed explanation

Work done \( W = -U_i \) \( U_i = 3 \frac{k q^2}{r} \) \( W = -3 \frac{(9 \times 10^9 \, \text{N} \cdot \text{m}^2/\text{C}^2) (10 \times 10^{-6} \, \text{C})^2}{10 \times 10^{-3} \, \text{m}} \) \( W = -3 \frac{9 \times 10^9 \times 10^{-10}}{10^{-2}} \)…