Concepts/Formulas Used:

Time constant for capacitor:

Where R is the resistance through which the capacitor is being charged/discharged and C is the capacitance.

Capacitance of a parallel plate capacitor:

A capacitor consists of two conducting plates of area of cross section A each separated by a distance d. The capacitance if there is only vacuum between the plates is given by:

where ϵ₀ is the permittivity of free space.

Given,

Area of the plate,

(

Now, distance of separation:

Resistance ,

We know that,