Educational 0-200Ω 1.25A Rheostat - with 4mm Banana Posts

A rheostat is a type of variable resistor used to regulate current or voltage in an electrical circuit by changing its resistance. It operates by changing the position of a slider (drive) on a resistive wire or layer, allowing for a smooth or stepless change in resistance from zero to a maximum value. In practice, a rheostat is a type of potentiometer that uses only two of the three available terminals.

How does a rheostat work?

Variable Resistance:
A rheostat contains a coiled resistance wire or a layer of high-resistance material.

Slider (drive):
A sliding contact (slider) is located on the wire or layer, which connects to this material.

Changing Resistance:
Moving the slider allows for a change in the length of the wire through which the current flows, which affects its total resistance.

Current Control:
By changing the resistance, the current in the circuit can be regulated, consistent with Ohm's Law.

Application Examples

Old Devices:
Rheostats were once commonly used in DC motor starters and to regulate the wake-up current in electric machines such as trams.

Modern Applications:
In some specific applications, such as lighting or fan dimmers, rheostats (or their digital equivalents) still regulate light intensity and speed.

Laboratory Applications:
In laboratories, rheostats can be used as variable loads for testing devices.