The temperature coefficient of resistance of a semiconductor is:

Explanation

The temperature coefficient of resistance for a semiconductor is negative, indicating that its resistance decreases as temperature increases. This is because higher temperatures provide energy to electrons, pushing them into the conduction band and increasing the number of charge carriers, thus reducing resistance. In contrast, metals have a positive coefficient because increased atomic vibration at higher temperatures hinders electron flow, increasing resistance. Insulators, with negligible charge carriers, show little change in resistance with temperature, and thus might be considered to have a zero coefficient. The concept of an imaginary coefficient is not applicable in this context.