A parallel plate capacitor with plate area ' A ' and distance of separation ' d ' is filled…

A parallel plate capacitor with plate area 'A' and distance of separation 'd' is filled with a dielectric. What is the capacity of the capacitor when permittivity of the dielectric varies as:

εx=ε0+kx, for 0<xd2

εx=ε0+kd-x, for d2xd

  1. ε0+kd22/kA
  2. kA2ln2ε0+kd2ε0
  3. 0
  4. kA2ln2ε02ε0-kd

Solution

Taking an element of width dx at a distance xx<d/2 from left plate 

dc=(ε0+kx)Adx

Capacitance of half of the capacitor 

1C=0d/21dc=1 A0d/2dxε0+kx

1C=1kAlnε0+kd/2ε0

Capacitance of second half will be same

Ceq=C2=kA2ln2ε0+kd2ε0

Asked in: JEE Main 2021 (25 Jul Shift 1)

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