a. A steady current flows in a metallic conductor of non - uniform cross section. State which of the quantities i.e., current density, electric field, and drift velocity remain constant?
b. A steady current passes through a cylindrical conductor. Is there an electorn field inside the conductor?

Explanation

### Step-by-Step Solution

#### Part A:
1. **Understanding Current Density (J)**:
- The current density \( J \) is defined as the current per unit area. Mathematically, it is expressed as:
\[ J = \frac{I}{A} \]
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