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### Course: Physics archive>Unit 10

Lesson 1: Discovery of magnetism

# Neutralize a compass

How to neutralize a compass using two needles. How could this help us later? Why does this work? Created by Brit Cruise.

## Want to join the conversation?

• If you would take out the second needle, would remaining needle STAY neutralized because of its close interaction with the other needle, or would it regain its ability to tell the direction?
• Interesting experiment. I would expect that the needle would not stay neutralised. Only the compass is neutralised (because it has two opposing needles and their magnetic field cancel one another); the magnetisation of the needle itself is not neutralised, just as if you put two magnet close together they do not lose their magnetism.
• When the needle is magnetized, why doesn't it demagnetize when you put it in water? Isn't the needle magnetized because there is lodestone dust on it? Would it wash off the needle over time?
• Every material capable of being magnetized has what are called "domains". When a magnet strokes a material like iron that can become a magnet, it aligns the domains a specific way. Here, the particular alignment is undone by the presence of a nearby magnet with its own domains that exert influence. That's why you shouldn't store magnets together!
• How to neutralize a compass using two needles. How could this help us later? Why does this work?
• I think this could help you determine the orientation of an unknown magnetized needle. Put it side-by-side, pointing in same direction, with a needle of known orientation, and if they neutralize each other then they are of opposite orientations.
• Do these videos help in practical experiments related to magnetism?
• What would happend if you put a third needle?
• It would matter if you stroked it with the north or south side of the magnet.
(1 vote)
• so if u put two needles it never hits south or north how come ?
(1 vote)
• What would happend if you put an other
(1 vote)
• now I get it ! the nails each hold an ammount of magnetism forcing them to point to the highest magnetised points of the Earth but when they are connected they scramble each other in a fight to look for the magnetised points making them' LOST '