JEE Main20199 Jan 2019Evening ShiftPhysicsCapacitanceActual
A parallel plate capacitor with square plates is filled with four dielectrics of dielectric constants K 1 , K 2 , K 3 , K 4 arranged as shown in the figure. The effective dielectric constant K will be:
Options
- AK = K 1 K 2 K 1 + K 2 + K 3 . K 4 K 3 + K 4
- BK = K 1 + K 2 K 3 + K 4 2 K 1 + K 2 + K 3 + K 4
- CK = ( K 1 + K 4 ) ( K 2 + K 3 ) 2 K 1 + K 2 + K 3 + K 4
- DK = K 1 + K 2 ( K 3 + K 4 ) K 1 + K 2 + K 3 + K 4
Correct answer
A. K = K 1 K 2 K 1 + K 2 + K 3 . K 4 K 3 + K 4
Step-by-step solution
C 1 and C 2 are in series. The equivalent capacitance of C 1 and C 2 is C 12 = ∈ 0 A 2 d 2 K 1 + d 2 K 2 = ∈ 0 A d K 1 K 2 K 1 + K 2 C 3   and   C 4   are in series C 34 = ∈ 0 A 2 d 2 K 3 + d 2 K 4 = ∈ 0 A d K 3 K 4 K 3 + K 4 C e q = C 12 + C 34 = ∈ 0 A d K 1 K 2 K 1 + K 2 + K 3 K 4 K 3 + K 4 ∴ K e q = K 1 K 2 K 1 + K 2 + K 3 . K 4 K 3 + K 4