In an experiment, a circuit is set up so that a capacitor with a resistor in series can be charged and at some later time discharged through the same resistor without changing the positions of the components.
The supply has a potential difference (p.d.) of 9.0 V9.0\text{ V}9.0 V d.c. The capacitor has capacitance 2.2 μF2.2\ \mu\text{F}2.2 μF. The resistor has resistance 4.7 kΩ4.7\text{ k}\Omega4.7 kΩ.
Calculate the charge QQQ stored on the capacitor when it is fully charged.
Use a calculation to explain why it will not be possible to measure the variation of p.d. across the capacitor with time, using a manual stopwatch.
State how this experiment can be modified to measure the variation of p.d. across the capacitor with time as the capacitor discharges.
The capacitor was completely charged and then discharged until its p.d. fell to 5.50 V5.50\text{ V}5.50 V.
Calculate the time ttt required for the p.d. across the capacitor to reach 5.50 V5.50\text{ V}5.50 V when discharging.
Calculate the average rate at which energy is lost by the capacitor as it discharges from 9.0 V9.0\text{ V}9.0 V to 5.50 V5.50\text{ V}5.50 V.
