Discharging a Capacitor problem 4

The potential difference (p.d.) across the resistor is equal to the potential difference (p.d.) across the capacitor.

The current flowing through the circuit causes the capacitor to lose charge and since the charge in a capacitor is proportional to the potential difference across it, the potential difference across the capacitor therefore decreases as it loses charge.

This therefore implies that the potential difference across the resistor also decreases as that of the capacitor decreases since they are always equal. Thus, the rate of change of the potential difference across the resistor decreases as its potential difference decreases. Hence, the reason for the shape of the line representing the variation of with .