The reason behind "moving magnetic field creates electric current"

[jerryyu]

I had been thinking lately about why moving magnet perpendicular to a wire causes electric current.

my conclusion is that the changes in magnetic strength ignites the electrons to move since a magnet's strongest field comes from its N point and basically what a moving magnet is doing is changing its field strength.

 

Please help me out if my logic is wrong since I haven't been taking physic since junior high

[swansont]

I had been thinking lately about why moving magnet perpendicular to a wire causes electric current.

my conclusion is that the changes in magnetic strength ignites the electrons to move since a magnet's strongest field comes from its N point and basically what a moving magnet is doing is changing its field strength.

 

Please help me out if my logic is wrong since I haven't been taking physic since junior high

 

Yes, that's basically Faraday's law: a changing field induces a potential for an open circuit or a current in a closed one.

[jerryyu]

if I wrapped a coil around an iron bar, put a capacitor and a battery on the wire and also do the same with the second coil that I also wrapped around. The only difference is that the voltage that will be produced from one coil is higher than the other coil and the capacitor is there to make sure the moving electrons from the first coil won't intervene with the moving electrons from the second coil. Will that also create a moving magnetic field?

 

Sorry if it is hard to visualize by the way it was written there, tell me and I will try to word it in a different way.

[swansont]

Yes, but the field will decrease exponentially over time and so will the current, as the capacitor charges up. So the induced current in the second will similarly decrease.

[jerryyu]

as the capacitor from the first coil charges up, the current from the second coil will start to flow; as the capacitor from the second coil charges up, the current from the first coil will start to flow

 

The field will only decrease as the batteries begin to drain out right?

 

I don't understand what you mean by the field will decrease exponentially over time and so will the current, as the capacitor charges up

[swansont]

I'm assuming the coils are unconnected; the capacitor will charge up and the current in such a circuit decreases exponentially.

[jerryyu]

I might be my lack of interpretation because I don't know what you're saying, I think we're viewing two different picture there.

[swansont]

If you have a battery and a capacitor as your circuit, the capacitor will charge up. The current in the circuit will decrease exponentially as this happens. It gets more complicated with an inductor in the circuit, but that's the basic behavior.

 

It might help to draw a circuit diagram to show what the situation you're envisioning looks like.

[jerryyu]

Ok well I have 2 coils around the iron bar, making it two battery and two capacitor. As the first capacitor charges up, the second capacitor will release the charged energy; and as the second capacitor charges up, the first capacitor will release its energy. And the two battery will release two different voltages- high and low. So as the wires combine, it will make a pattern like this--high, low, high, low- and so on.

 

I was thinking that if that will produce an iron bar with changing magnetic field, thus can also produce electricity when a wire is wrapped around it.

[Jacques]

A transformer is basically like your two coils around the iron bar. Transformer work with alternative current, that mean that the magnetic field produced by the primary is changing (high- low -high -low...) wich cause an alternating current in the secondary. The ratio of the peak voltage depend on the ratio of the number of turns.

Battery produce direct current, and what I think you are trying to do with you capacitor is to produce an alternating current. That is possible if you add and active device like a transitor to cycle the capacitor from charging to discharging.

[jerryyu]

Thanks Jacques