A $50 \mathrm{cm}$ long wire is moving in a uniform magnetic field of $0.8 \mathrm{N} {\mathrm{A}}^{-1} {\mathrm{m}}^{-1}$ with a velocity of $2 {\mathrm{ms}}^{-1}$ perpendicular to both its length and the magnetic field. Calculate the induced emf in the wire. If the wire be moving parallel to the field, what will be the value of the induced emf?

An aeroplane, the distance between the edges of its wings being 30 m, is landing down with a velocity of 300 km h-1. If, while landing, the wings of the aeroplane be east-west, find out the potential difference between the edges of the wings be north-south, then? (Given : ${\mathrm{B}}_{\mathrm{H}}=0.4\times {10}^{-4}\mathrm{T}$).