A rod made of conducting material is in a region of uniform magnetic field. It is moved horizontally along two parallel conducting rails X and Y. The other ends of the rails are connected by a thin conducting wire.

The speed of the rod is constant and is also at right angles to the direction of the uniform magnetic field.

(a) (i) Describe, with reference to the forces acting on the conduction electrons in the rod, how an emf is induced in the rod.

(a) (ii) An induced emf is produced by a rate of change of flux. State what is meant by a rate of change of flux in this situation.

The length of the rod in (a) is 1.2m and its speed is 6.2ms^–1. The induced emf is 15mV.

(b) (i) Determine the magnitude of the magnetic field strength through which the rod is moving.

(b) (ii) Explain how Lenz’s law relates to the situation described in (a).