Question

Read the following statements carefully
$Y:$ The resistivity of a semiconductor decreases with increase of temperature
$Z:$ In a conducing solid, the rate of collisions between free electrons and ions increases with increase of temperature
Select the correct statement $(s)$ from the following:

• A. $Y$ is true but $Z$ is false
• B. $Y$ is false but $Z$ is true
• C. Both $Y$ and $Z$ are true
• D. $Y$ is true and $Z$ is the correct reason for $Y$

Answer 1

Answer: (C)

In case of semiconductor Resistivity $\alpha \frac{1}{\text{ temperature }}$
In this case as temperature increases electrons jump to conduction band resistance decreases Rap(Resistivity) so resistivity also decreases and current increases.
Vibration of electrons increases with rise in temperature and hence collision between ions and electrons increases with temperature.