A parallel-plate capacitor with plate are `20cm^(2)`and plate separation 1.0mm is connected to a battery .The resistance of the circuit is `10k(Omega)`.Find the time constant of the circuit.

Explanation

`A = 20 cm^2 = 20 xx (10^-4) m^2 `
` D= 1 mm = 1 xx (10^-3) m , `
` R = 10 K Omega `
` C = epsilon_0 A /d `
` = (8.85 xx (10^-12) xx 20 xx (10^-4)/1 xx (10^-3))`
` = (8.85 xx (10^-12) xx 2 xx (10^-4) / (10^-3)) `
` = 17.7 xx (10^-12) ` farad .
` Time constant = CR `
` = 17.7 xx (10^-12) xx 10 xx (10^3) `
` = 17.7 xx (10^-8) `
` 0.177 xx (10^-6) s `
` = 0.18 mu s ` .