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-   -   Neodymium magnet and electromagnet experiment (http://physicshelpforum.com/electricity-magnetism/13678-neodymium-magnet-electromagnet-experiment.html)

yafimski Sep 15th 2017 10:56 AM

Neodymium magnet and electromagnet experiment
 
Hi,

I wanted to repel away a standard neodymium magnet by using an electromagnet. I got a nail, some coil, a neo magnet and a 9v battery.

I wrapped some coil on the nail, and attached it to the battery.

The problem is that the neo magnet attaches to the nail regardless if the nail is magnetized or not... I thought the electromagnetic nail will have N/S poles when attached to a current, therefore producing a repel effect on the neo magnet.

I am probably wrong about some crucial assumption... can someone help me understand?


Thanks

Woody Sep 15th 2017 11:22 AM

I suspect that your neodymium magnet is simply overwhelming your electromagnet.

Try testing their relative strengths (by seeing how many pins, or small nails, or other similar objects, each can pick up in a single lift).

Another way of looking at it is that the battery is trying to push the electrons one way around the coil,
While the neodymium magnet is trying to push them the other way round the coil.

Sounds like the neodymium magnet is winning.

yafimski Sep 15th 2017 11:32 AM

Thanks! I will try to increase the coils or get a weaker magnet.

oz93666 Sep 15th 2017 09:22 PM

If this is a small 9v battery used in domestic products it just won't deliver the current required ...

To get a decent magnetic field you have to match the coil resistance , number of turns , and battery, to get the best output ... thicker the wire , lower resistance , so more current ...but thicker wire means less turns in a coil ... it's a balancing act .... a car battery or supply that can deliver many amps is required .

magnetic field is proportional to n x I ..n the turns in the coil .... I is current ..

yafimski Sep 16th 2017 02:02 AM

Ah okay, it might be that multiple parameters should be adjusted. I will check the formulas and try to figure it out and update if more help is needed :)

Thank!

Pmb Sep 23rd 2017 12:38 PM

Quote:

Originally Posted by oz93666 (Post 37077)
If this is a small 9v battery used in domestic products it just won't deliver the current required ...

To get a decent magnetic field you have to match the coil resistance , number of turns , and battery, to get the best output ... thicker the wire , lower resistance , so more current ...but thicker wire means less turns in a coil ... it's a balancing act .... a car battery or supply that can deliver many amps is required .

magnetic field is proportional to n x I ..n the turns in the coil .... I is current ..

It would be very unwise to use a low resistance wire and a car battery since the coil will short out the battering causing the wire to heat up and melt and there is a risk of the battery to exploding.

oz93666 Sep 23rd 2017 09:21 PM

Quote:

Originally Posted by Pmb (Post 37189)
It would be very unwise to use a low resistance wire and a car battery since the coil will short out the battering causing the wire to heat up and melt and there is a risk of the battery to exploding.

Risk of a car battery exploding !!! never ....

You can directly short a car battery and it will not explode ... they can handle 100's of Amps ...

Pmb Sep 23rd 2017 10:26 PM

WARNING: Do NOT listen to oz. He's advice is DANGEROUS!


Quote:

Originally Posted by oz93666 (Post 37193)
Risk of a car battery exploding !!! never ....

You can directly short a car battery and it will not explode ... they can handle 100's of Amps ...

You don't read things very closely, do you? I said "risk" which means its not a certainty. But it can and does happen. but not in all cases at all times. You really need to stop talking about things you don't understand when its as dangerous as this claim of yours.

Stop being ignorant and please learn about what I just explained to you. It's quite clear that you're a know-it-all since otherwise you'd have looked up what I explained and known better than to respond with such an ignorant statements as that. It's just plain [i]dangerous[i]. When a car battery is shorted out it doesn't merely pass a few hundred amps but thousands of amps. Car batteries contain hydrogen gas. If there is a spark caused by the high current, such as when connecting the leads with a wire causing a short, it can ignite the hydrogen gas which will then explode.

Read more about this at
https://blogs.lawyers.com/attorney/a...ry-risk-39150/

For example
Quote:

Tools being placed between battery terminals: Some people test batteries by placing a screw driver across the terminals to see if an arc jumps and is therefore supplying electrical energy. Unfortunately this can be dangerous because the current sent through the screw driver is not regulated; it can be very high and cause an explosion.

Cripes. You can do a search and watch it happen in a YouTube video

Here's an example of what oz claims can't happen



The car battery explosion is 12 seconds in.

yafimski Sep 24th 2017 12:59 AM

Hi,

Thanks for the answers.
I would like to keep the discussion in the realms of informative responses. I think we've cleared up explosions enough :)

So far I've increased from 65 turns to 130 turns around the nail. I'm using the 9v battery. How much current should I use? (since there is still no effect of the electromagnet on the neomagnet).


Thanks!

yafimski Sep 24th 2017 12:59 AM

The neomagnet is here:
5pcs New 20x3mm Neodymium Disc Super Strong Rαre Earth Magnets With Holes 5mm | eBay


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