In a practical potentiometer, why is a rheostat used in series to a potentiometer wire? As we move the jokey the primary circuit current will also change. So, can we cause the same amount of current flow by changing resistance?
[Physics] Use of rheostat in a practical potentiometer
electric-circuitselectrical-resistanceelectricity
Best Answer
The potentiometer is used to compare voltages by matching them. At the balancing point no current flows through a galavanometer between the potentiometer circuit and the test circuit, so it does not disturb the test circuit.
The potentiometer is most sensitive when, at the balancing point, the slider or jockey is towards, but not too close to, the end of the potentiometer wire. The rheostat allows you to adjust the voltage across the potentiometer so that the balancing point is in the most sensitive region.