Physics Circle home Student Login

Home›Chapters›Capacitors PYQs›Dielectrics›Question 80

JEE Main 2021 (16 Mar, Shift 1) · Dielectrics

Dielectrics question from JEE Main 2021 (16 Mar, Shift 1)

Q80JEE Main 2021 · 16 MAR · SHIFT 1Medium

Dielectrics

For changing the capacitance of a given parallel plate capacitor, a dielectric material of dielectric constant K is used, which has the same area as the plates of the capacitor. The thickness of the dielectric slab is 34\frac{3}{4} d, where 'd' is the separation between the plates of parallel plate capacitor. The new capacitance (C') in terms of original capacitance (C0) is given by the following relation:

Show answer and solution

Answer: (c)

  1. C′=ϵ0A(d−t)+tKC'=\frac{\epsilon_0A}{(d-t)+\frac{t}{K}} with t=3d4t=\frac{3d}{4}.
  2. C′=ϵ0Ad4+3d4K=ϵ0Ad⋅4KK+3C'=\frac{\epsilon_0A}{\frac{d}{4}+\frac{3d}{4K}}=\frac{\epsilon_0A}{d}\cdot\frac{4K}{K+3}
  3. So the answer is (c) C′=4KK+3C0C'=\frac{4K}{K+3}C_0.
Report a mistake

More questions on Dielectrics