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Question 31518
JEE Physics · Hard

Capacitance: Energy With Dielectric – Isolated MCQ

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Energy With Dielectric – IsolatedHardQuestion 31518

Question

When a dielectric (constant K) is inserted into an isolated charged capacitor, the energy stored:
  1. A
    Increases by K
  2. B
    Decreases by factor K
    Correct
  3. C
    Stays the same
  4. D
    Doubles

Correct answer

Decreases by factor K

Explanation

U = Q²/2C. With Q fixed and C→KC, energy becomes U/K. The energy decrease goes into work done against the attractive force pulling the slab in.

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