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Two 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:

Asked in NEET 2025 · Charge sharing between conductors

• (1) (3F)/5
• (2) (2F)/3
• (3) F/2
• (4) (3F)/8

Step-by-step solution

Why the other options are wrong

• (1) No single slip gives (3F)/5; the charges end as q/2 and (3q)/4.
• (2) No single slip gives (2F)/3; the charges end as q/2 and (3q)/4.
• (3) Counts only the contact with A (q/2 and q) and forgets that the third sphere then shares its charge with B.

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