CAPE Physics Unit 2 · 2006 · Paper 2 · Question 5(a)(iii)

Questions on magnetic fields, magnetic forces between conductors, and current balances.

Figure 5 shows two long parallel wires, both of length l, separated by a distance r, carrying currents I_1 and I_2 in opposite directions. Show that the force between the two wires is given by F = \frac{\mu_0 I_1 I_2 l}{2\pi r}, and state whether this force is attractive or repulsive.

This question uses a figure or table from the paper — you'll see it when you practise.