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Physics · PYQ NEET UG 2025
हिन्दीTwo identical charged conducting spheres A and B have their centres separated by a certain distance. Charge on each sphere is \( q \) and the force of repulsion between them is \( F \). A third identical uncharged conducting sphere is brought in contact with sphere A first and then with B and finally removed from both. New force of repulsion between spheres A and B (Radii of A and B are negligible compared to the distance of separation so that for calculating force between them they can be considered as point charges) is best given as :
Correct answer · Option 4
\( \frac{3F}{8} \)
Explanation
Initial charges are \( q_A = q, q_B = q \). After touching A with uncharged sphere, \( q_A' = q/2 \). After touching B with this, \( q_B' = \frac{q + q/2}{2} = 3q/4 \). New force \( F' \propto q_A' q_B' = \frac{q}{2} \cdot \frac{3q}{4} = \frac{3}{8} q^2 = \frac{3}{8} F \).
