What is current density? Write the vector equation connecting current density J with electric field intensity E for an ohmic conductor.

Explanation

### Step-by-Step Solution:

1. **Definition of Current Density**:
- Current density (denoted as \( \mathbf{J} \)) is defined as the amount of electric current flowing per unit area of a cross-section. Mathematically, it can be expressed as:
\[ \mathbf{J} = \frac{I}{A} \]
where \( I \) is the current flowing through the conductor and \( A \) is the cross-sectional area.
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