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CUET · PHYSICS · PYQ PAPER 2025

Three parallel plates (each of area A) are separated by distances \( d_1 \) and \( d_2 \) respectively. The in-between spaces are filled with dielectrics of relative permittivity \( \epsilon_1 \) and \( \epsilon_2 \). The permittivity of free space is \( \epsilon_0 \). The capacitance of the combination is:

  1. A \( \frac{\epsilon_0 \epsilon_1 \epsilon_2}{\epsilon_2 d_1 + \epsilon_1 d_2} \)
  2. B \( \frac{\epsilon_0 \epsilon_1 \epsilon_2 A}{\epsilon_2 d_1 + \epsilon_1 d_2} \)
  3. C \( \frac{\epsilon_2 d_1 + \epsilon_1 d_2}{\epsilon_0 \epsilon_1 \epsilon_2 A} \)
  4. D \( \frac{\epsilon_1 \epsilon_2 A}{\epsilon_2 d_1 + \epsilon_1 d_2} \)
Verified Solution

Answer & Solution

Correct Answer

(B) \( \frac{\epsilon_0 \epsilon_1 \epsilon_2 A}{\epsilon_2 d_1 + \epsilon_1 d_2} \)

Step-by-step Solution

Detailed explanation

\( C_1 = \frac{\epsilon_0 \epsilon_1 A}{d_1}, C_2 = \frac{\epsilon_0 \epsilon_2 A}{d_2} \) \( \frac{1}{C_{total}} = \frac{1}{C_1} + \frac{1}{C_2} = \frac{d_1}{\epsilon_0 \epsilon_1 A} + \frac{d_2}{\epsilon_0 \epsilon_2 A} \)…