This is a circuit used to investigate the discharge of a capacitor, and a graph showing the change in current with time when the capacitor is discharged.

Deduce the resistance $R$ of the resistor.

This is a circuit used to investigate the discharge of a capacitor, and a graph showing the change in current with time when the capacitor is discharged.

Explain why the current decreases as the capacitor discharges.

This is a circuit used to investigate the discharge of a capacitor, and a graph showing the change in current with time when the capacitor is discharged.

The charge on the capacitor is equal to the area under the graph. Estimate the charge on the capacitor when the potential difference across it is $9.0 \mathrm{V}$.

Figure 1 shows a circuit used to investigate the discharge of a capacitor, and Figure 2 is a graph showing the change in current with time when the capacitor is discharged.

Calculate the capacitance of the capacitor.

The spherical dome on a Van de Graff generator has a diameter of $40 \mathrm{cm}$ and the potential at its surface is $5.4\mathrm{kV}$.

Calculate the charge on the dome.

The spherical dome on a Van de Graff generator has a diameter of $40 \mathrm{cm}$ and the potential at its surface is $5.4\mathrm{kV}$.

Calculate the capacitance of the dome.

An earthed metal plate is moved slowly towards the sphere but does not touch it. The sphere discharges through the air to the plate. This graph shows how the potential at the surface of the sphere changes during the discharge.

The spherical dome on a Van de Graff generator has a diameter of  $40 \mathrm{cm}$ and the potential at its surface is $5.4 \mathrm{kV}.$ Calculate the energy that is dissipated during the discharge.

Show that the capacitance $\mathrm{C}$ of an isolated conducting sphere of radius $\mathrm{r}$ is given by the formula: $\mathrm{C}=4\pi {\epsilon }_0\mathrm{r}$.