Question

Iron and silicon wires are heated from 30°C to 50°C. The correct statement is that :

(a) resistance of iron wire decreases

(b) resistance of iron wire increases and that of silicon wire decreases

(c) resistance of iron wire decreases and that of silicon wire increases

(d) resistance of both wires increases

Answer 1

Correct option (b) resistance of iron wire increases and that of silicon wire decreases

Explanation:

Iron is a metal and silicon is a semiconductor. The resistivity of metal is directly proportional to its absolute temperature but the resistivity of semiconductor is inversely proportional to its absolute temperature. Hence, resistivity of metallic wire like iron increases and resistivity of silicon wire decreases with the increase of temperature.