An electron is moving north; what direction should a magnetic
field be oriented, so the magnetic force on the electron just
balances the gravitational force?
A square loop is in the x-y plane, with its top and bottom
parallel with the x-axis, and its sides parallel with the y-axis.
It carries a clockwise current when viewed from the positive
z-axis. There is a constant magnetic field
pointed in the x-axis direction. What are then
directions of the magnetic forces on the four...