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Name: judy a sims
Status: N/A
Age: N/A
Location: N/A
Country: N/A
Date: 1999


Question:
My fifth graders would like to know - Why does the compass needle always point to the north?


Replies:
A compass needle is a magnet (a weak one), and it tends to line up in such a way as to point its "north pole" towards the North Pole of the planet. Why? Because the Earth is also a magnet! It's filled with a dense iron core and so it gives off a magnetic field. To investigate this, get two bar magnets, and a compass. Notice that the compass points north. Now, take one of the bar mangnets and slowly move it near the compass. You will see the compass needle "follow" the magnet. Since the bar magnet is close up, the needle "feels" the magnetism of the bar more strongly than that of the Earth. Now, take the bar magnet away and watch it point north again.

Put the compass aside and play with the two bar magnets. Notice that when you bring the two poles together which are the same ((N-N or S-S) you get a different result than if you bring them together N-S or S-N. Now, try laying one magnet on the table. Take the other magnet anduse it to "move" the first magnet the same way you moved the compass needle, by waving it nearby and using the magnetic force to move it without the two magnets actually touching each other (you need good, strong magnets - or light ones - to do this. Why?).

Hope this helps answer your question....the Earth is a giant magnet, (this is becauseof the molten iron core at the Earth's center) and thus it rotates light magnets to point at its north pole.

-dr topper



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