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Friday, 9 October

JEE Main 2025 · PhysicsMultiple choiceDiagram basedMediumMulti-step

JEE Main 3 April 2025, Shift 1, Physics Q38

Question 38 of 75 in this shift, Physics question 13 of 25, Section A.

A parallel plate capacitor is filled equally(half) with two dielectrics of dielectric constants ϵ1\epsilon_1 and ϵ2\epsilon_2, as shown in figures. The distance between the plates is d and area of each plate is A. If capacitance in first configuration and second configuration are C1C_1 and C2C_2 respectively, then C1C2\frac{C_1}{C_2} is :

The figure, in words

First configuration: two dielectric slabs stacked one above the other between horizontal plates (epsilon_2 on top, epsilon_1 below), each of thickness d/2. Second configuration: slabs side by side (epsilon_2 left, epsilon_1 right), each covering half the plate area.
  1. (1)ϵ0(ϵ1+ϵ2)2\frac{\epsilon_0(\epsilon_1 + \epsilon_2)}{2}
  2. (2)4ϵ1ϵ2(ϵ1+ϵ2)2\frac{4\epsilon_1\epsilon_2}{(\epsilon_1 + \epsilon_2)^2}Official answer
  3. (3)ϵ1ϵ2ϵ1+ϵ2\frac{\epsilon_1\epsilon_2}{\epsilon_1 + \epsilon_2}
  4. (4)ϵ1ϵ22(ϵ1+ϵ2)2\frac{\epsilon_1\epsilon_2^2}{(\epsilon_1 + \epsilon_2)^2}

Official answer

Option 2

NTA final key.

Chapter
Electrostatic Potential and Capacitance
Topic
Dielectrics
Idea tested
Identifying Series vs Parallel Slab Configurations

Same topic in other shifts

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Question text from the official JEE Main paper published by NTA; answer from the final answer key. Chapter, topic and idea tags, difficulty and skill are Lumi’s. This question needs a figure we do not reproduce; it is described in words above. Lumi analyses 42 of the 174 JEE Main shifts held from 2017 to 2026.