In the figure shown the four rods have `lambda` resistance per unit length. The arrangement is kept in a magnetic filed of constant magnitude `B` and directed perpendicular to the plane of the figure and direction inwards. Intially the sides as shown from a square. Now each wire starts moving with constant velocity `v` towards opposite wire. Find as a function of time:
(a) induced emf in the circuit
(b) induced current in the circuit with direction

Explanation

After time `t`
Net emf : `e=2B.2v(l-2vt)=4Bv(l-2vt)`
`i=(e)/(R)=(4Bv(l-2vt))/(4lambda(l-2vt))=(Bv)/(lambda)` , clockwise