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(C) The temperature dependence of resistivity $\rho$ for a conductor is given by $\rho = \rho_{0}[1 + \alpha(T - T_{0})]$,where $\alpha$ is the temper

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Increases,decreases

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(C) The temperature dependence of resistivity $ho$ for a conductor is given by $ho = ho_{0}[1 + \alpha(T - T_{0})]$,where $\alpha$ is the temperature coefficient of resistivity.For a conductor,as temperature increases,the amplitude of vibration of lattice ions increases. This leads to more frequent collisions between free electrons and ions,which decreases the relaxation time $	au$. Since resistivity $ho = m / (ne^2	au)$,a decrease in $	au$ causes the resistivity to increase.For a semiconductor,as temperature increases,more valence electrons gain enough thermal energy to jump across the energy gap into the conduction band. This significantly increases the number density of charge carriers $n$. Since $ho \propto 1/n$,the increase in $n$ dominates,causing the resistivity to decrease.

By increasing the temperature,the specific resistance (resistivity) of a conductor and a semiconductor,respectively,is:

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