# Is magnetic flux constant?

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1. Oct 29, 2014

### 21joanna12

I know that the equation for magnetic flux is $\Phi=\int \vec{B} \cdot dA$. It seems to me that this is like integrating the density function a rod with respect to x, which simply gives you the mass which is constant. I was wondering whether the same thing applies here: is magnetic flux a constant?

2. Oct 29, 2014

### Matterwave

In general, no it is not. A changing magnetic flux leads to an EMF by way of Farday's law.

3. Oct 30, 2014

### Staff: Mentor

The density function $\rho(x)$ of a rod does not normally change, nor do its dimensions. The magnetic field $\vec B$ can change, and so can the boundary of the surface that we integrate over.