(a)[1]
State the SI base units for force.
(b)
As shown in Fig. 1.1, two wires of length $l$ are arranged parallel to one another with a separation of $x$. Each wire carries current $I$. The currents produce a force $F$ on each wire, given by $F = \dfrac{K I^2 l}{x}$, where $K$ is a constant.
(b(i))[2]
Find the SI base units of $K$.
(b(ii))[2]
On Fig. 1.2, sketch how $F$ varies with $x$. Keep $I$ and $l$ constant.
(b(iii))[1]
The current $I$ in both wires is changed. On Fig. 1.3, sketch how $F$ varies with $I$. Keep $x$ and $l$ constant.