How do I make a coil cover half of a circle

[Strange]

19 minutes ago, DARK0717 said:

How much resistance does a coil make in comparison to the repelling force of an n52 magnet

The resistance of a coil depends on the length and thickness of the wire. (And what it is made of.)

The repelling force of a magnet depends on the strength of the two magnets and the distance. (Nearby it will be an inverse square law, becoming an inverse cube law at greater distance. I think.)

You cannot relate these two things. It is like asking "how much flavour does a strawberry have in comparison to the fuel economy of a Ferrari"

[DARK0717]

The magnets inside the pistons are quite close to each other. The method I think of to "turn off" the magnets is by matching the poles using an electromagnet from within a metal attached to them both

It is similar to this

Edited September 28, 2019 by DARK0717

[Externet]

If you had one of these, would it make you happy ?

----> https://www.enginediy.com/products/v8-electromagnetic-engine-8-coils-engine-model

[Enthalpy]

If the generator shall provide one positive and one negative smooth pulses per turn, it's called a two-poles alternator.

Then the good design lets a magnet be the rotor, and the coil surrounds it at the stator. Called Gramme design. Check the drawing there
https://en.wikipedia.org/wiki/Alternator
https://en.wikipedia.org/wiki/File:Alternator_1.svg

Iron at the stator is useful, among others to shield the world from the dangerous magnetic field, but with rare-earth magnets the iron is not mandatory for a decent induction.