(a)[1]
State the meaning of an electric field.
(b)[4]
An isolated solid metal sphere has radius $R$. The charge on the sphere is $+Q$ and the electric field strength at its surface is $E$. On Fig. 5.1, draw a line to show how the electric field strength varies with distance $x$ from the centre of the solid sphere for values of $x$ from $x = 0$ to $x = 3R$.
(c)[3]
The sphere in (b) has radius $R = 0.26\,\text{m}$. Electrical breakdown (a spark) occurs when the electric field strength at the surface of the sphere exceeds $2.0 \times 10^{6}\,\text{V m}^{-1}$. Determine the greatest charge that can be stored on the sphere before electrical breakdown occurs.