Effect of Temperature on Resistance:

In ideal conditions, resistance is the constant element of the circuit. But as the current flows, heat is generated, and temperature is enhanced. With enhance in temperature following effects are observed:

 (a) Resistance of the metal conductors increases with increase in temperature. The Resistance-temperature graph is a straight line and shown in Figure

Figure: Resistance-Temperature Curve for Metals

(b) Resistance of alloy also rise with increase in temperature. But this raise is relatively slow and irregular.

(c)  Resistance of semiconductors reduce with raise in temperature. At very low temperature, they acts like insulators but at high temperature they show the property of conductors.

(d) Resistance of electrolytes and insulators (bad conductors) drop with increase in temperature.