Answer
Eddy current brakes will work on copper and aluminum wheels as well, not just on ferromagnetic wheels.
Work Step by Step
As discussed in section 20-6 on page 600, the external magnetic field interacts with the mobile conduction electrons in a metal wheel to cause the braking effect. The eddy currents appear in the moving metal wheel and experience a magnetic force. By Lenz’s Law, this effect will oppose the original motion of the piece of metal that caused the eddy currents to form. Thus, the eddy current brake slows the wheel down.
There is no reference whatsoever to the ferromagnetic nature of the wheel’s material. The only requirement is that the wheel be a good electrical conductor.
In truth, copper and aluminum are even better conductors than iron, meaning they will provide a larger eddy current braking effect.
