A capacitor of capacitance C is given a charge Q. At t = 0, it is connected to an ideal battery of emf ϵ through a resistance R. Find the charge on the capacitor at time t.

Note that and .


Concepts/Formulas used:


Kirchhoff’s loop rule:


The sum of potential differences around a closed loop is zero.


Capacitance:


If two conductors have a potential difference V between the them and have charges Q and -Q respectively on them, then their capacitance is defined as




Let the potential across the capacitor be at time t be Vc. Let the charge at time t be q. The initial charge is Q.



Applying Kirchhoff’s loop rule ,







We know that




Using the property : , we get



Note that at any time,





Thus, we can remove the modulus,






2