Prove that the force acting on a current - carrying wire, joining two fixed points a and b in a uniform magnetic field, is independent of the shape of the wire.
Force on a current carrying wire in a uniform magnetic field
l = length of wire,
i = current,
B = Magnitude of magnetic field
Since F = ilB
Now, since the length of the wire is fixed from A to B, so force is independent of the shape of the wire.