what is megnetic Flux ? how it changes? with some examples.
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Here’s a quick, simple definition I found: “Magnetic flux is the measurement of the total magnetic field which passes through a given area” -khan academy
Here’s an [image](https://cdn.kastatic.org/ka-perseus-images/144a93251811f0dd92a084a73d2222e96dd2241b.svg) to help visualize. The gray planes on the top and bottom are given as the north and south poles of the magnet. The blue plane is the surface you want to measure the magnetic flux for. And the red arrows are the magnetic field lines.
I’ll also list the equation for magnetic flux, Φ = B*A*cosθ.
B – magnetic field strength
A – area of surface you’re measuring
θ – angle between surface and magnetic field line
Take a circular coil of wires and place a magnet near it. There will be a certain direction that the magnetic field takes from the magnet. A certain amount of that magnetic field will pass through the circular area of the coil of wires. This is the magnetic flux.
Now, if you change the magnetic flux, a current is induced in the wires. There are a few ways to change the magnetic flux. If you look back at the equation above, we can see that the magnetic flux, Φ, will change if B (magnetic field strength), A (area), or θ (angle between area and magnetic field) changes.
The magnetic field strength, B will change if you vary the distance between the magnetic and the coil of wires. The area, A can change if you expand or contract the coil. The angle, θ can change by either rotating the magnet or the coil of wires.
This is the core concept of how a generator works. Take a wind turbine for example. There is a loop of wire in the hub that is connected to the blades. As the wind causes the turbine blades to spin, the wire loop also spins. This loop of wire rotates around a magnetic. This rotation changes the angle between the magnetic field and the area of the loop thus changing the magnetic flux and therefore inducing a current.
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