dumb question about ELECTROmagnets

[freefuelplz]

I made an electro magnet out of an iron nail and some wire and battery today. I also broke 2 relays apart and used the electromagnet inside to test some thing. I COULD NOT get any opposition out of anything. Can electromagnets oppose? I could only get them to attract. I know its a dumb question.

[Feynman]

I think this is a great question


Electromagnets can oppose.    BUT I suspect they must be very strong for this to happen.   Your electromagnets are probably attracting because they are not strong enough.  Let me show you an example of how I think this can happen.




Now, the easiest way to get them more powerful is to do more turns of wire per unit length.  You can also increase the supply voltage.


Additionally, make sure you are wrapping your coil in the same direction.  That is, if you wrap clockwise,  make sure you wrap clockwise the entire length of the electromagnet.  Follow the "right hand rule" to make sure your B-field doesn't cancel itself.



You can tell which way B (the magnetic field) will point by the "Right Hand Rule" and taking your hand, curling your fingers in direction of the current i , and seeing which way your thumb points.  Try it on the diagram. Curl your fingers in the direction of i (in the coil) and stick your thumb out.

You will see your thumb points in the direction of B, the magnetic field.  (right to left, like this <---  )

[freefuelplz]

Thanks for the great response. If what i was trying to oppose was a strong permanent magnet, then would it work better? In other words, is it only because of the iron cores that they wont oppose easily?

[Low-Q]

I made an electro magnet out of an iron nail and some wire and battery today. I also broke 2 relays apart and used the electromagnet inside to test some thing. I COULD NOT get any opposition out of anything. Can electromagnets oppose? I could only get them to attract. I know its a dumb question.

If you have two magnets, iron cored electromagnets or permanent magnets, where equal poles are facing, they can attract eachother if one magnet is much stronger than the other, and they are close enough. This happens typically in electromotors. They does not start running spontaneously if the current through the windings in the rotor is too weak. Magnets are made of ferro magnetic materials, and a strong magnet will attract to that feromagnetic material even if the polarity of that object is facing it's equal pole. However, if you have two aircoils, equal poles will allways repel as long there is electric current flowing through the coils.

br.

Vidar

[Tempest]

Are you using ac or dc to power them?