(a(i))[2]
State the meaning of electric potential at a point.
(a(ii))[1]
Define the term capacitance.
(b)
Figure 4.1 plots how the potential $V$ of an isolated metal sphere varies with the charge $Q$ on its surface.
(b(i))[2]
Use Fig. 4.1 to find the sphere’s capacitance.
(b(ii))[2]
Use Fig. 4.1 to find the electric potential energy stored on the sphere when its potential is $150\ \text{kV}$.
(c)[2]
A spark lowers the sphere’s potential from $150\ \text{kV}$ to $75\ \text{kV}$. Calculate the energy lost by the sphere.