# PHY C23: Magnetic Flux

New chapter! Let’s start off with a very important concept:

• Magnetic Flux
• Φ = BA sin θ

Remember my post on Magnetic Flux Density?

Now we turn to a similar term:

# Magnetic Flux

What is magnetic flux?

## The product of magnetic flux density & cross-sectional area normal to the lines of flux.

It is represented by Φ

For a uniform field B making an angle θ with a cross-sectional area A,

## Φ = BA sin θ

Its unit is the weber (Wb)

## 1 Weber is equal to 1 Tesla multiplied by 1 meter-squared

Wb = Tm2

Confusing? Let’s look at that 3D image illustrating B again: Here, the cross-sectional are A is perpendicular to the magnetic field lines.Φ = BA

Let’s look at the general case now: Here, the cross-sectional are A is at an angle θ to the magnetic field lines.Φ = BA sin θ

Now let’s compare different cross-sections for different areas & different magnets:

We’ve seen why flux density is so important – it is useful in calculating the forces exerted by a magnetic field.

So…

Why is magnetic flux so important?
It is useful in explaining Electromagnetic Induction.

We’ll cover that in my next post – see you there!