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JEE Main202117 Mar 2021Morning ShiftPhysicsCapacitanceActual

A parallel plate capacitor whose capacitance C is 14 pF is charged by a battery to a potential difference V = 12 V between its plates. The charging battery is now disconnected and a porcelain plate with k = 7 is inserted between the plates, then the plate would oscillate back and forth between the plates with a constant mechanical energy of _______ pJ . (Assume no friction)

Correct answer

0

Step-by-step solution

U i = 1 2 × 14 × 12 × 12   pJ    ∵ U = 1 2 C V 2 = 1008   pJ U f = 1008 7 pJ = 144   pJ    ∵ C m = k C 0 Mechanical energy = Δ U = 1008 - 144 = 864   pJ

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