Rheostat

The schematic symbol for the rheostat is shown in Figure 57. A rheostat is a variable resistor used to vary the amount of current flowing in a circuit. Figure 58 shows a rheostat connected in series with an ordinary resistance in a series circuit. As the slider arm moves from point A to B, the amount of rheostat resistance (AB) is increased. Since the rheostat resistance and the fixed resistance are in series, the total resistance in the circuit also increases, and the current in the circuit decreases. On the other hand, if the slider arm is moved toward point A, the total resistance decreases and the current in the circuit increases.