According to the definition of conductivity `(sigma=J//E)`, electric field is being considered to exist inside a conductor but according to electrostatics of conductor , electric field cannot exist inside its volume.
Explain the difference and state the condradiction if any.

Explanation

### Step-by-Step Solution:

1. **Understanding Conductivity**:
- Conductivity (σ) is defined as the ratio of current density (J) to the electric field (E) within a conductor. The formula is given by:
\[ \sigma = \frac{J}{E} \]
- This implies that when an electric field is applied to a conductor, it causes charges (typically electrons) to move, resulting in a current.
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