A Compass at the South Pole

This experiment comes from a question sent to me by a subscriber. His question was, "If I were standing directly on the South Pole and I was holding a compass, where would the needle be pointing?"

Lets do this scientifically. Before you read on or try the experiment, think about it. Think about what you know about magnets. Think about how a compass works. Once you have come up with an idea of what you think would happen, then you will be ready to try this.

To answer this question, you will need:

  • a magnet
  • a needle
  • wax paper
  • water

First, we will make a compass. Hold the needle by the end away from the point. Rub one end of the magnet along the needle, from your fingers towards the point of the needle. Always use the same end of the magnet and always move the magnet from your fingers towards the point. Then move the magnet away from the needle, and back to its original position. Repeat this about 30 times to magnetize the needle.

Fill the bowl with water. Cut a small square of waxed paper, about an inch square. Float the paper in the water and place the needle on it. This will allow the needle to float freely and it should point north. Be sure that there are no magnets or metal objects nearby, as they will interfere with the compass.

Depending on which end of the magnet you used to rub the needle with, either the point or the base of the needle will point north. That is the north pole of the magnetized needle.

We are going to use the magnet to simulate the Earth. To do that, we need to identify the poles of your original magnet. Bring the magnet near your compass. Opposites attract, so the north pole of your needle will point towards the south pole of your magnet. Mark that end with an N. Yes, I said an N, not an S. I know that south starts with an S, but there is a reason for this. Think about it. Opposites attract, right. But the north pole of the compass points towards the north pole of the Earth! That is because the geographic north pole is actually a magnetic south pole. That is why it attracts the north pole of your compass.

Now that you have the south pole of your magnet marked with an N, mark the other end with an S. Your magnet is now set to simulate the Earth's magnetic field. Now, bring the south pole of your "Earth" near the compass. Where does the north pole point? Away from it, right? The same thing would happen at the Earth's geographic south pole. The north end of your compass would try to point away from it, pointing nearly straight up! It is not completely straight up because the Earth's magnetic poles are not exactly lined up with the geographic poles, but they are close enough together for this example.

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