JEE Advanced 2020 Concept Recapitulation Test 3 Paper 1

A rod of mass M=3kg and radius 5cm rests on two parallel rails that are d (10cm) apart and L(2m) long. The rod carries a current I=50A (in the direction shown) and rolls along the rails without slipping. If it starts from rest at one end. And a uniform magnetic field of magnitude 0.4T is directed perpendicular to the rods and the rails. It leaves the rail at a speed of ‌

K

3

m∕s. Find K.