Figure shows a wire sliding on two parallel, conducting rails placed at a separation ℓ. A magnetic field B exists in a direction perpendicular to the plane of the rails. What force is necessary to keep the wire moving at a constant velocity v?

Question

Philoid · Accepted Answer

Given:

Velocity of wire=v

Separation between rail=l

We know that,

Force experienced by a wire of length l carrying current I in a magnetic field B and placed perpendicular to magnetic field is given by

Now since here there is no formation of closed circuit the circuit is open and the current flowing in the wire =0

Therefore, force experienced by wire due to magnetic field =0

Hence net force on wire becomes zero and it moves with constant velocity v

Therefore, no external force is needed to move the wire with velocity v