A Problem of Wires on the Rails
It’s been a long time since I posted a cute physics problem so here’s one about magnetism for your edification and/or amusement.
Two long wires are laid flat on a pair of parallel rails perpendicular to the wires. The spacing d between the rails is large compared with x, the distance between the wires. Both wires and rails are made of material which has a resistance ρ per unit length. A magnetic flux density B is applied perpendicular to the rectangle formed by the rails and the wires. One wire is moved along the rails with uniform speed v while the other is held stationary. Derive a formula to show how the force on the stationary wire varies with x and use it to show that the force vanishes for a value of x approximately equal to μ0v/4πρ.
Give a physical interpretation of this result.
HINT: Think about the current induced in the wires…Follow @telescoper