Topic: Energy stored in a capacitor· Electrostatics

A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system :

1. decreases by a factor of 2

2. remains the same

3. increases by a factor of 2

4. increases by a factor of 4

Doubtly Asked 30 Oct 2026 NEET UG 2017 Practice test neet Save WhatsApp Report

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Answer: 1. decreases by a factor of 2

Key idea: charge is conserved when the second capacitor is connected, but energy is not.

Initially \(U=\dfrac{Q^2}{2C}\). After connecting in parallel the capacitance is \(2C\) with the same charge \(Q\): \(U'=\dfrac{Q^2}{2(2C)}=\dfrac{Q^2}{4C}\).

So energy halves; half is lost as heat in the connecting wires.

Doubtly AI · 30 Oct 2026 AI-generated · not yet verified Report

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A capacitor is charged by a battery. The battery is removed and another identical uncharged capacitor is connected in parallel. The total electrostatic energy of resulting system :

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