What is induced emf? State Fleming's right hand rule for the direction of this emf and explain with the help of a diagram.

A rectangular conductor, L M N O, is placed in a uniform magnetic field $\overrightarrow{\mathrm{B}}$, directed perpendicular to the plane of the conductor, as shown in Fig. $9.58$. Obtain an expression, for the emf induced in the arm M N, when the arm is moved towards the left (parallel to itself) with a speed v. Use the above expression to find the emf induced between the ends of an axle, of length L, of a railway carriage, travelling on level ground, with speed v. Assume the value of earth's magnetic field at the place to be B and the angle of dip to be $\mathrm{\theta }$