- This is useful for demonstrating the motion of a conductor in a magnetic field.
- It comprises of a star-shaped toothed copper disc, capable of rotating vertically on a pair of adjustable bearings at each side.
- The disc dips into a mercury trough positioned between the two arms of a small horseshoe magnet, on a wood base.
- The disc holding clamp is adjustable vertically on a metal support rod, which is connected to one of the two terminals mounted on as base.
- The other terminal is connected to the mercury trough.
- The apparatus operates on 4 Volts, at which voltage it takes 1.8 amps of current.
- It is supplied without battery.