How spinning produces electricity?


How do spinning things like wind/water turbines or those spin to charge flash lights make electricity by just spinning?

In: Engineering

It does so by spinning a magnet through a coil of wire. The magnet passing through the coil essentially creates a flow of electricity from one side to another.

It is because of the phenomenon of “induction”. If you pass electric current through a conductor like a wire it will cause a magnetic field around it, like with the electromagnets you likely made in school. If a conductor is exposed to a changing magnetic field it will cause or “induce” an electric current to flow in the conductor.

Electric motors use current flow through coils of wire to create changing magnetic fields which spin the motor’s shaft. Electric generators spin coils of wire through magnetic fields to cause current in the wire. Spinning is a good way to pass wire through those fields, as it keeps everything in the same general area as opposed to continually shooting off in some direction.

There are special kinds of fluid pumps out there that work like this: they have a flexible tube that is pressed up against a rotating wheel. This wheel has bumps on it that pinch against the tube. As the wheel spins, the pinch point moves along the tube, effectively squeezing a bit of liquid through the tube like a tube of toothpaste, or yogurt, or those freezie pop treats.

At a very high level, a common electrical generator works in somewhat the same way, except instead of pinching a tube with little nubs the generator “pinches” a wire with magnets, and instead of fluid getting squeezed through a tube, electrons are being “squeezed” through a wire.

A generator (and motor) has two main parts. A ring with copper wire wrapped around it called a stator and part that can spin in the middle of the ring called a rotor.

The wind or water spins a turbine. The turbine is connected the rotor so causes it to spin.

The rotor design can vary but for what is called a synchronous generator they also have a loop or winding of copper wire and this wire is connected to a DC source so has DC current in it.

When the wind or water turns the turbine, and thus the rotor, induction happens. I explain that here. It applies to generators because motors and generators are essentially the same type of machine but operating from opposite ends.

So OK. You know atoms exist, right? They’re tiny particles that everything’s made out of.

Atoms are made out of even smaller particles. One of those kinds of particles is “electrons”. Atoms are supposed to have a specific number of electrons, but doing certain kinds of things can add or take away from those electrons. Moving electrons around like that is what makes electricity.

A magnetic field can move electrons. So if you spin a magnet near a wire coil, it’s sort of pushing electrons through the wire. The moving electrons are electricity!

Thing thing to keep in mind is that electricity is not the electrons themselves, but their movement. One of the handy-er ways to think about electricity is to use a water analogy.

Imagine that the there’s a coil of water tubing around a turning magnet, like if you wrapped a tube around the edges of a fan.

Now imagine that magnet can grab the water molecules, with a magnetic field. When the turning magnet pulls the water “down” or “up” it pushes or pulls the water in the coil.

Eventually the tube/coil heads away from the magnet to do something useful, and because of water pressure, even once the water is away from the magnet, the water behind it keeps it moving.

It’s not a great model but it gives me a handy visual.