⚛️ Physics · Electrostatic Potential and Capacitance · NEET & JEE

A parallel plate capacitor is charged and disconnected. One plate is moved to double the gap. Energy stored:

Answer: Doubled.

A Halved
B Same
C Doubled
D Quadrupled

Correct answer: C. Doubled

Explanation: Disconnected: Q constant. C = epsilon0 A/d. If d doubles, C halves to C/2. U = Q2/(2C). New U = Q2/(2 x C/2) = Q2/C = 2U. Energy doubles.

Radial electric field lines and concentric red equipotential lines around a point charge (an electron), with field lines pointing inward

Field lines (radial) and equipotential lines (concentric circles) of a point charge. Equipotential surfaces are always perpendicular to the field lines. Image: Sjlegg, Public Domain, via Wikimedia Commons.

Concept context

Electric potential, equipotential surfaces, potential energy of charge systems, conductors, dielectrics, capacitors, combinations, and energy storage.

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A parallel plate capacitor is charged and disconnected. One plate is moved to double the gap. Energy stored:

Concept context

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