Define linear charge density and write its SI units.

Explanation

### Step-by-Step Solution:

1. **Definition of Linear Charge Density**:
- Linear charge density is defined as the amount of electric charge per unit length along a line. It quantifies how much charge is distributed over a certain length.

2. **Mathematical Representation**:
- Linear charge density is represented by the symbol \( \lambda \).
- The formula for linear charge density can be expressed as:
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