Question

A semiconductor is cooled from T1k to T2k then its resistance will ............

Answer 1

$\bold{\text{ans: increases}}$

explanation :- actually resistivity depends upon the temperature in such way :
$\rho = \rho_0[1+\alpha(T_f-T_i)]$
where α coefficient of resistivity e.g., constant for specific matter . in case of semiconductor α be negative . hence, if we increases the temperature then, resistivity will be decreases . it means resistance will be decreases. but when temperature decreases then resistivity increases and hence, resistance increases.

here, semiconductor is cooled , means temperature decreases then, resistivity increases and hence, resistance increases .

that's why resistance will be increases after cooling of semiconductor.

Answer 2

A semiconductor is cooled from T1k to T2k then its resistance will  increase.

Explanation :
A semiconductor has negative temperature coefficient of resistance .
As Temperature increases, semiconductor resistance decreases.

Therefore when a semiconductor is cooled, its resistance will increase.