In an experiment where a magnet is falling through a wire, the flux density is presented by the top graph in the image. Why is the graph not a straight line like the one below it?
I thought that if flux density is the product of area, magnetic field strength, and cosine of the angle between them, then $\cos(x)$ is either $1$ or $-1$. Thereby we don't have a cosine-function.
We simply have, Magnetic flux density = field strength * area. Shouldn't that be a straight line, or am I missing something crucial?
(The flux density has an upwards direction as positive).