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MHT CET 2024 (16 May, Shift 1) · Dielectrics

Dielectrics question from MHT CET 2024 (16 May, Shift 1)

Q45MHT CET 2024 · 16 MAY · SHIFT 1Medium

Dielectrics

Two identical capacitors A and B are connected in series to a battery of E.M.F., 'E'. Capacitor B contains a slab of dielectric constant K, QAK,\ Q_{A} and QBQ_{B} are the charges stored in A and B. When the dielectric slab is removed, the corresponding charges are QA′Q'_{A} and QB′Q'_{B}. Then

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Answer: (d)

  1. In series QA=QBQ_A = Q_B always.
  2. With slab: Ceq=KC⋅C(K+1)C=KCK+1C_{eq} = \frac{KC \cdot C}{(K+1)C} = \frac{KC}{K+1}, so Q=KCEK+1Q = \frac{KCE}{K+1}.
  3. Without slab: Ceq=C2C_{eq} = \frac{C}{2}, so Q′=CE2Q' = \frac{CE}{2}.
  4. QB′QB=QA′QA=K+12K\frac{Q'_B}{Q_B} = \frac{Q'_A}{Q_A} = \frac{K+1}{2K}
  5. So the answer is (d).
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