(a)[1]
State what electric field strength means.
(b)[2]
An isolated metal sphere A, with radius $26\,\text{cm}$, carries a positive charge, as shown in Fig. 6.1. Electrical breakdown, which produces a spark, happens when the electric field strength at the sphere’s surface goes above $2.0 \times 10^{4}\,\text{V m}^{-1}$. Calculate the maximum charge $Q$ that may be held on the sphere. $Q = \ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots C$
(c)[2]
A second isolated metal sphere B, which also has charge $+Q$, has radius $52\,\text{cm}$. Calculate the extra charge, in terms of $Q$, that can be placed on this sphere before electrical breakdown takes place. additional charge = \ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots\ldots