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**Writing the expression for magnetic flux:**

Laws of Electromagnetic induction are heavily centered around the concept of magnetic flux $ϕ_{B}$ and its variation with time. So it is very important to learn how to write magnetic flux through any closed area. The area is considered as vector.

We can look at the expression B A $cosθ$ in two ways:

We can look at the expression B A $cosθ$ in two ways:

- B (A $cosθ$) i.e., B times the projection of area normal to B, or
- B$⊥$A, i.e., component of B along the normal to the area element times the magnitude of the area element.

$Φ_{B}=B_{1}.dA_{1}+B_{2}.dA_{2}+...=∫B.dA$

Let us have a better understanding of magnetic flux crossing an area A through this video.

Introduction of Magetic flux

7 mins