Identify the correct statement among the following.

Options

A. Resistivity of metals decreases with temperature because more electrons are available for conduction
B. Resistivity of metals increases with temperature because number of electrons decreases.
C. Resistivity of metals increases with temperature because number of collisions between electrons increases
D. Resistivity of metals decreases with temperature because superconductivity sets in.

Answer

C

Explanation

When the temperature of a metal is increased, the atoms in it starts to vibrate more rigorously. This leads to increase in number of colisions amongst the electrons. Thus, time between successive collision or relaxation time `'tau'` decreases. Since, the resistivity of a metal is given by
`rho=m/(n e^(2) tau)`
Where, m = mean of electron,
n = number of charge and
e = charge on electron
`implies rho alpha 1/tau`
So, on `tau` decreases, resistivity 's' increases.