Question

The solids which have negative temperature of coefficient resistance are.
(a) Insulator
(b) Semiconductors
(c) insulators and semiconductor
(d) metals

Answer 1

Hint :The temperature of coefficient of resistance of any solid depends upon its resistivity against the electric current semiconductor insulators have higher electrical resistance. If increase in temperature, then decrease in the temperature coefficient of resistance of solid.

Complete Step By Step Answer:
Resistance is the ability of the material to resist the current which changes as change in temperature. Insulators like wood and plastic have high resistance when temperature is low. If temperature increases, the resistance coefficient decreases. Similarly, the semiconductors have resistance. Lower than insulators but higher than conductors.
Temperature coefficient of resistance,
 $\mathrm{\Delta }R=\alpha R\mathrm{\Delta }T$
Where,
 $\mathrm{\Delta }R=$ change in resistance
 $\mathrm{\Delta }T=$ change in temperature
 $R=$ Initial resistance
 $\alpha =$ Coefficient of resistance temperature.

Note :
Copper, gold, platinum like materials have high conductivity and low resistance hence its temperature coefficient is positive as its resistance increases with increase in temperature. Opposite to the insulators and Semiconductors.