Two long wires are placed on a pair of parallel rails perpendicular to the wires. The spacing between the rails d is large compared with x, the distance between the wires. Both wires and rails are made of a material of resistivity `rho` per unit length. A magnetic flux density B is applied perpendicular to the rectangle by the wires and rails. One wire is moved along the rails with a uniform speed v while the other is held stationary. Determine how the force on the stationary wire varies with x and show that it vanishes for a value of x approximately equal to

Answer

`(mu_(0)v//4pi rho)`.