The magnetic brake is based on Faraday's law
When the flux of a magnetic field, through a surface, is changing with time, an induced force appears.
To simulate a brake, a source of DC is needed
A metal disc is also used, which is joined to a dock so it can rotate
and two copper coils, connected to the source of DC, so that a magnetic field is created between them
This can be observed when the source is connected and a probe is inserted between the coils
To simulate the magnetic brake, the disk is rotated
The disk is released and the source is connected
As the disc surface through which is passing the magnetic field is changing with the time, eddy currents appear
These currents are in the magnetic field, so a magnetic force appears that is opposing the rotation of the disc
