The resistivity of a metal is a function of temperature because

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  1. The electron density varies with temperature.
  2. The electron gas density varies with temperature.
  3. The lattices vibration increases with temperature.
  4. Collision of electrons increases as temperature increases.

Answer (Detailed Solution Below)

Option 4 : Collision of electrons increases as temperature increases.
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Detailed Solution

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Concept:

Mobility (μ): It is defined as the ratio of Drift velocity to the Electric field.

\(\mu = \frac{{{V_d}}}{E}\)

It also describes how fast is the charge carrier moving from one place to another.

Electron mobility is greater than hole mobility.

Explanation:

As temperature increases, the atoms in the material will vibrate and due to these thermal vibrations, the mobility of the charge carrier reduces.

As

\(\mu \propto {T^{ - m}}\)

where,

m = 2.5 for electron

m = 2.7 for holes in case of silicon

Hence electrical conductivity of metal has a negative temperature coefficient.

So as temperature increases,

Mobility decreases due to which collision of electrons increases with an increase in temperature.

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