North and south pole in an electromagnet

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Discussion Overview

The discussion revolves around determining the north and south poles of an electromagnet, particularly in the context of a locking device that utilizes a neodymium magnet and an electromagnet. Participants explore the behavior of electromagnets, the direction of current flow, and the implications for the design of the locking mechanism.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested
  • Homework-related

Main Points Raised

  • One participant inquires about how to determine the north and south poles of an electromagnet and whether these poles remain constant when current is applied.
  • Another participant describes the right-hand grip rule to determine the direction of the north pole based on the current flow in the coils.
  • There is a discussion about the direction of current flow in a battery, with some participants asserting that current flows from negative to positive, while others reference conventional current flow from positive to negative.
  • A participant expresses uncertainty about the flow of electrons and the implications for the hand rules used in electromagnetism.
  • One participant asserts that with direct current, the poles of the electromagnet should remain in the same position each time it is activated.
  • A participant shares frustration regarding their homemade electromagnets, noting that one end attracts both ends of their neodymium magnets and seeks advice on achieving the desired repulsion and attraction.

Areas of Agreement / Disagreement

Participants express differing views on the direction of current flow and its implications for electromagnet behavior. There is no consensus on the effectiveness of the homemade electromagnets or the specific behavior of the poles in relation to the neodymium magnets.

Contextual Notes

Some participants reference the conventional direction of current flow versus the actual flow of electrons, highlighting potential confusion regarding terminology. The discussion includes unresolved questions about the behavior of the electromagnets in practical applications.

Who May Find This Useful

Individuals interested in electromagnet design, current flow in circuits, and practical applications of electromagnetism may find this discussion relevant.

brandontran87
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Not sure if this should be in engineering or physics section. Sorry if I got it wrong.

How do I determine the north and south pole in an electromagnet? Do electromagnets have a constant N or S pole?

I am making a locking device where a neo magnet will hold a lid down tightly by sticking itself to a piece of steel placed inside the enclosure. I want to make that piece of steel an electromagnet so that when it turns on it will repel the neo magnet enough so I can open the lid. But to do that I need to be able to determine the poles on the electromagnet and keep it constant every time I run a current through the coil.

If I wrap the coil around the middle of the piece of steel will the opposite ends of the steel be the N or S poles?

Thanks in advance guys. If you guys have any suggestions for my project I would love to hear it. =)
 
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right hand grab rule:

If you grab the electromagnet in your hand with the current in the coils flowing in the direction of your fingers, then if you stick your thumb out, it points in the direction of the magnet's north pole. Current is assumed to travel from the positive end of the battery to the negative.
 
current flows from the negative to the positive in a battery. the electrons are pushed away from the negative and attracted to the positive.
 
oops :blush:
 
cragar said:
current flows from the negative to the positive in a battery. the electrons are pushed away from the negative and attracted to the positive.

But the hand rules, left hand rule etc use the conventional( +to -) current direction.
 
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I think it's positive to negative...http://en.wikipedia.org/wiki/Electric_current#Current_flow I think positive means there is an abundance of electrons so they move to a negative? Not sure...

Anyways, do you guys think my idea will work? If I turn the electromagnet on, will the poles stay at the same spot every time?
 
with direct current, yes the poles should stay in the same place.
 
I agree with dadface and that is why I wrote "Current is assumed to travel from the positive end of the battery to the negative." (for hand rules) :)
 
k I am sure you guys are right about the hand rules and everything , but how can electrons flow from positive to negative , maybe i am missing something.
 
  • #10
cragar said:
k I am sure you guys are right about the hand rules and everything , but how can electrons flow from positive to negative , maybe i am missing something.

You are not missing something the true direction is from -to +.The hand rules use the incorrect conventional direction which goes the other way.I think these rules were devised long before the true current direction was known and for some reason they have remained in the texts.
 
  • #11
ok thanks for clarifying
 
  • #12
Hi
some one please help/ i am ready to throw a screaming fit...

I HAVE HOME MADE ELECTRO MAGS...THEY ARE GOOD ONES...POWERED BY A 12 VOLT CAR BATTERY (DC),...WHY IS IT THAT ONE END OF THE ELECTRO MAGNETS...EITHER NORTH OR SOUTH WILL ATTRACT BOTH ENDS (NORTH OR SOUTH ) OF MY NEODYMIUM MAGNETS ...TRIED EVERYTHING...EVEN SOBBING INTO MY PILLOW . WHAT I NEED IS FOR ONE END OF THE ELECTRO, EITHER NORTH OR SOUTH TO REPEL ONE END OF THE NEO AND ATTRACT THE OTHER END OF THE NEO...BEGGING FOR HELP...JIM
 
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