(a(i))[1]
A wire coil ABCD is positioned between the poles of a magnet. X and Y are connected to a commutator and a battery. State why there is a force on side AB of the coil.
(a(ii))[2]
Describe how the commutator keeps the coil turning in one direction.
(b(i))[2]
The motor current is $2.0\,\text{A}$ and the battery e.m.f. is $12\,\text{V}$. Over $8.0\,\text{s}$, the motor does 140 J of work. Calculate the energy supplied to the motor in $8.0\,\text{s}$.
(b(ii))[1]
Calculate the motor’s efficiency.