Concepts/Formulas used:

Charging a capacitor:

A capacitor of capacitance C is being charged using a battery of emf ϵ through a resistance R . A switch S is also connected in series with the capacitor. The switch is initially open. The capacitor is uncharged at first. At t=0, the switch is closed

The charge is at any t>0 is given by:

Note that is known as time constant.

Given,

Capacitance,

EMF of battery,

Resistance,

We also know that at ,

We know that,

Taking natural logarithm on both sides, we get

Now,