Two wires carrying equal currents i each, are placed perpendicular to each other, just avoiding a contact. If one wire is held fixed and the other is free to move under magnetic forces, what kind of motion will result?
Using the relation for force acting on a conductor
Where
I is the current in the wire,
L is the length vector of the wire
B is the external electric field.
Thus, if the wires are kept perpendicular, the angle between them will be 90
and thus the angle between the movable wire and the magnetic field due to the fixed wire is 0
( from Maxwell’s Cork-Screw rule). Thus the force is the minimum and it is in an unstable equilibrium. Thus the will rotate and make itself parallel to the fixed wire and attain the maximum attractive force and thus a stable equilibrium.