What is a plate rheostat?

Question

images of plate rheostat

Answer 1

A rheostat is an electronic device that changes the voltage as ONE contact slides across bare copper wires that are coiled up.

For example, ten inches of thin copper wire are coiled around a flat PLATE that is only 1/4 inch long.  As one contact slides from left to right, the voltage RESISTANCE changes from 12 volts down to 3 volts.

A needle gauge with this flat rheostat might indicate your petrol tank is full or near empty.  It might indicate the water teperature to be cold or hot.

It might allow your electric train to run fast or slower.  Many uses.

Sometimes the rheostat is a circular coil, with a DIAL that you can turn to change the voltage.