(a(i))[1]
State Coulomb’s law describing the force between two point charges.
(a(ii))[3]
Two point charges lie in a vacuum and are separated by a distance $R$. The force between the charges is $F_C$. On Fig. 5.1, sketch a graph to show how the force $F$ between the charges changes with separation $x$ for values of $x$ from $x = R$ to $x = 4R$.
(b)
Coils C and D are placed close to each other, as shown in Fig. 5.2.