Question

Place two tiny current segments on (1,0,0) and (0,1,0), each heading to positive x direction and positive y direction. By magnetic force dF= idl × B, the segments will be driven to positive y direction and positive x direction respectively, resulting in a non-zero net internal force in the system of two segments. This is because momentum can be carried by the fields. But the case above is impossible because there is no current segment; it has to form a closed loop. So, in the case it is a closed loop of current, is it possible that it creates a non-zero net internal force?

Answer 1

The net force on a closed loop of current in a uniform magnetic field is zero due to the cancellation of forces on each segment of the loop. However, there can be a net torque on the loop.

Step-by-step explanation:

The net force on a closed loop of current in a uniform magnetic field is zero. The net force on a closed loop of current in a uniform magnetic field is zero due to the cancellation of forces on each segment of the loop. However, there can be a net torque on the loop.

This is because the forces on each segment of the loop cancel out due to Newton's third law of motion. Although each segment of the loop experiences a force, the net force on the loop as a whole is zero. However, there can be a net torque on the loop, which is calculated using the magnetic dipole moment and the magnetic field strength.