Define the term electrical conductivity of a metallic wire. Write its SI unit.

Explanation

### Step-by-Step Solution

1. **Definition of Electrical Conductivity**:
Electrical conductivity of a metallic wire is defined as the ability of the wire to conduct electric current. It is the reciprocal of resistivity, which means that it indicates how easily electric current can flow through the wire. Mathematically, it can be expressed as:
\[ \sigma = \frac{1}{\rho} \]
where \(\sigma\) is the electrical conductivity and \(\rho\) is the resistivity.
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