Question

A parallel plate air condenser has a capacity of 20µF. What will be the new capacity if the distance between two plates is doubled? 

Answer 1

Capacitance between the parallel plates of the capacitor, C = 20 pF

Initially, distance between the parallel plates was d and it was filled with air. Dielectric constant of air, k = 1

Capacitance C, is given by the formula,

C = `(k∈_0A)/d`

= `(∈_0A)/d`

C = `(Ain_0)/d = 20muF`

if `d' -> 2d        :. C' -> C/2 = 10 muF`