Define magnetic flux . Give its `SI` unit. `I`

Explanation

### Step-by-Step Solution:

1. **Definition of Magnetic Flux**:
Magnetic flux (Φ) is defined as the total number of magnetic field lines passing through a given surface area in a magnetic field. It quantifies the amount of magnetic field that penetrates through a surface.

2. **Mathematical Representation**:
The magnetic flux can be mathematically expressed as:
\[
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