Define resistivity of a conductor. Plot a graph showing the variation of resistivity with temperature for a metallic conductor. How does one explain such a behaviour, using the mathematical expression of the resistivity of a material

Explanation

### Step-by-Step Solution

**Step 1: Define Resistivity of a Conductor**
Resistivity (ρ) is a fundamental property of a material that quantifies how strongly it resists the flow of electric current. It is defined as the resistance of a uniform material of unit length and unit cross-sectional area. The unit of resistivity is ohm-meter (Ω·m).

**Step 2: Mathematical Expression for Resistivity and Temperature**
The resistivity of a metallic conductor varies with temperature and can be mathematically expressed as:
\[
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