Question

The magnetic force acting on a charged particle can never do work because at every instant the force is perpendicular to the velocity. The torque exerted by a magnetic field can do work on a current loop when the loop rotates. Explain how these seemingly contradictory statements can be reconciled

Short answer

No, the torque doesn’t work in a rotating current loop

Step-by-step solution

What is torque?

Torque is the measurement of the force that can cause an object to rotate about any given axis. It is rotational, force is what causes an object to accelerate in liner motion.

Explanation

Now, we know that the magnetic force that the moving charged particle experiences is perpendicular to the velocity, hence the work done is zero. On the other hand, the magnetic field that is acting on the current carrying conductor is perpendicular to the length. Now the torque is perpendicular to the force and the rotation of the loops are also in the same direction. That is why the torque does not work in a rotating current loop