posted by unknown .
A 0.2 kg conductor of length 0.8 m carries 2 ampere current to the right in a magnetic field. What is the magnitude and the direction of the magnetic field acting on the conductor if the net force on the rod is zero? (Assume that the rod is hung by two insulating supports.)
if there is no net force, the magnetic force BIL equals the weight, M g.
B = M g/(I L)
= 0.2*9.8/(2.0*0.8) = 12.25 T
The direction of the B field must produce an upward force. Use the right hand rule.