A capacitor is charged to a potential difference of 100 V and is then connected across a resistor. The potential difference across the capacitor decays exponentially with respect to time. After 1 sec, the P.D. between the plates of the capacitor is 80 V. what will be the potential difference between the plates after 2 sec ?

Options

A. 32 V
B. 48 V
C. 64 V
D. 70 V

Answer

C

Explanation

The decay is exponential and the voltage drops to 80% of its value in one second. At the end of second second, the voltage will be `80xx(80)/(100)=64V`