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JEE Main 2021 (27 Jul, Shift 1) · Dielectrics

Dielectrics question from JEE Main 2021 (27 Jul, Shift 1)

Q85JEE Main 2021 · 27 JUL · SHIFT 1Medium

Dielectrics

Two capacitors of capacities 2C and C are joined in parallel and charged up to potential V. The battery is removed and the capacitor of capacity C is filled completely with a medium of dielectric constant K. The potential difference across the capacitors will now be:

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Answer: (c)

  1. Charge: Q=3CVQ = 3CV, constant after the battery is removed.
  2. New capacitance: 2C+KC=(K+2)C2C + KC = (K+2)C.
  3. V′=3CV(K+2)C=3VK+2V' = \frac{3CV}{(K+2)C} = \frac{3V}{K+2}
  4. So the answer is (c).
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