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### Course: Physics library>Unit 18

Lesson 1: Discovery of magnetism

# Compass build (magnet orientation)

Making a Compass: does it matter if we stroke the needle with the North vs. South pole of the magnet? Why? Created by Brit Cruise.

## Want to join the conversation?

• Why do you have to but the styrophom ball on the needle?
• you need the styrofoam ball so the needle can float
• what happens if you pull the magnet side ways or to your left?

Thank you! :)
• This would not occur as there are no magnetic poles to the east or the west for the needle to align with. Only a north or south orientation may be achieved through magnetic forces because that is how the magnetic forces of the earth are aligned.

Polarity shifts do occur within the earth, meant that there are times in the Earth's history that Polar North is what we consider south. If this had occurred in written history the maps would probably have been written upside-down because our point of reference would have changed.
• why does he need to stroke a needle all the time instead of using a magnet or a magnetite?
• Indeed he could use a permanent magnet to show it points north but he wants to show us how a metal can be magnetized and that the direction of magnetism can be changed depending on the stroke direction.
• How do you know which way to stroke though? What if im lost and stroked the needle so it pointed south but i need to go north.
• when the south pole of the permanent magnet is facing down, the end of the needle at which you start is south and the other end of the needle is north. similarly when the north of the permanent magnet is facing down, the end at which you start will become the north pole of the needle.
• why does the needle point north?
• The needle does not really point north, but the material inside the metal itself lines up with the magnetic poles, north and south directions, positive or negative poles. (Not sure which direction is which pole.) I hope you find this helpful!
• What would happen to our planet if we had 4 magnetic poles like this: magnetic north, magnetic south, magnetic east, and magnetic west? Would we have western lights just after the sunset on the west side and just before sunrise on the east side and vice versa for eastern lights? Would we be more protected from CMEs?
(1 vote)
• poles are opposites - they exist in pairs. There couldn't be 4 poles because each pair would match up to the other - they wouldn't all 4 repel each other in balance- instead, each would attract an opposite.
• i don't get how it's pointing north..if you stroke it one way and it points in that direction and then you stroke it the other way and does the same thing, how am i to know which way is north or south it points in the direction i stroke it..sorry if this is a stupid question but i just don't see how it's easily north..it'd make more sense if it pointed in one direction regardless of the direction you stroke it for it to be easily determined where north is for sure..i know the natural science laws are proven but i really want to understand rather than just accept it..any response would be appreciated.
(1 vote)
• does it matter what type of plate you use?
(1 vote)
• If you're standing at the North Pole with your compass, where does the needle point??
(1 vote)
• what way does the needle point when you strike it towards the looped end?
(1 vote)
• It will still be the same as striking it toward the top(Lets say North) or bottom(Lets say South) This phenomenon is due to the needle being a linear shape. 180 deg. <Finite Line>
(1 vote)

## Video transcript

(distant sounds of traffic in background) (plunks on table) (metallic scraping) (metallic scraping) (plunks on table)