Rheostat: Working, Uses Complete Guide (2023)

Rheostat is a wire wound variable resistance.

Rheostat Diagram


It consists of a high resistance wire wound over an insulating cylinder. The ends of the resistance are connected to the two fixed terminals A and B. Third terminal C is attached to a sliding contact which can be moved over the wire.

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Rheostat Function/Uses

Rheostat can be used as:

  1. Variable Resistor
  2. Potential Divider

1. Variable Resistor

A Rheostat acts as a variable resistor when terminal A and sliding terminal C are connected in circuit. In this way resistance between A and C is used. If C is moved away from A, resistance increase and vice versa.

2. Potential Divider

The circuit of potential divider is shown:

Rheostat Potential Divider

Battery supplies voltage V across resistor R current is given by: I = V/R

Now voltage across BC = current x resistance

VBC = Ir

        = (V/R) (r)

‘r’ is resistance of wire between BC, which varies as sliding contact C moves. Now VBC changes with ‘r’.


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