What is electrical resistivity? What is its S.I. unit?

Explanation

### Step-by-Step Solution:

1. **Understanding Electrical Resistivity**:
- Electrical resistivity is a fundamental property of materials that quantifies how strongly a given material opposes the flow of electric current. It is important to note that resistivity is not the same as resistance. While resistance is a measure of how much a specific object (like a wire) resists current, resistivity is an intrinsic property of the material itself.

2. **Definition of Electrical Resistivity**:
- The definition of electrical resistivity can be stated as follows:
- **Electrical resistivity is the property of a material to obstruct the flow of electric current through a conductor.**
...