Make a compass using common materials and learn how to identify “north” to guide your way. Then use your homemade compass for interesting experiments.
How a Compass Works
The type of compass you make is a magnetic compass. A compass works by using a magnetized needle that aligns itself with the Earth’s magnetic field. One end of the compass needle is attracted to the Earth’s magnetic North Pole and points towards it. The other end of the compass needle is attracted to the Earth’s magnetic South Pole and points towards it.
Keep in mind, a magnetic compass points to magnetic north, which is different from true north. Magnetic north depends on the concentration of ferrous minerals deep in the Earth (which move over time). True north is north based on the Earth’s rotation. The difference between magnetic north and true north is the magnetic declination. Magnetic declination depends on where you are on the planet. Because of magnetic declination, a magnetic compass is not useful near the North or South Pole.
Being near iron-based materials or electromagnetic fields also affects a magnetic compass. Expect inaccurate results using your compass near power lines, automobile engines, magnets, etc. Ships use a gyroscopic compass instead of a magnetic compass. A gyrocompass uses the Earth’s rotation to point to true north rather than magnetic north.
How to Make a Compass
Materials
- Small magnet
- Sewing needle or metal paperclip
- A bowl of water
- A small piece of cork or foam or a leaf
Basically, you want a small thin piece of magnetic metal that acts as your compass needle. Then, you either pierce a small floating object or else rest the magnetized metal on the floating object. The liquid does not have to be water, but it’s readily available.
Make a Compass
- Magnetize the needle: Rub the needle across the magnet several times in one direction. This magnetizes the needle. If you don’t have a magnet, you have other options. One is striking the needle several times with a hammer or rock. Another (anecdotal) method is holding the pointy end of the needle and rubbing the eye against hair, fur, or silk 50-100 times to weakly magnetize the metal. (You’re better off hitting the metal with a rock.)
- Float the needle: Place the needle on top of the cork, foam, paper, or leaf and place it in the bowl of water. The needle spins until it aligns itself with the Earth’s magnetic field.
- Mark the needle: Once the needle has stopped moving, mark the end that is pointing towards the North with a permanent marker.
- Use the compass: You now have a homemade compass! To use it, hold it flat and level in your hand. The end that you marked as pointing North should point towards the North.
The magnetization of the needle is not permanent. Eventually, you need to magnetize it again and establish North.
How to Know Which Way Is North
Once you make a compass, you have to figure out which direction is North and which is South. You could flip a coin and hope for the best. Fortunately there are better ways of finding North.
- Use a map: If you have a map, use it and orient your compass. Rotate the map until the North on the map is aligned with the end of the needle that you marked as pointing North. If the landmarks line up, your direction is correct. Otherwise, turn the map around to South. Assuming the landmarks line up, the mark on your compass points South and the opposite direction is North.
- Look at the Sun: The Sun rises in the East and sets in the West. Facing sunrise, North is on your left. Facing sunset, North is on your right. During the day, the Sun is only directly overhead at the equator. In the northern hemisphere, it is to the South, while in the southern hemisphere, it is to the North.
- Look at the Stars: The North Star, also known as Polaris, is always in the same position in the sky relative to the Earth’s North Pole. Once you find the North Star, use your compass and determine North. If you can’t identify Polaris, look for the Big Dipper. It is also in the North. In the Southern Hemisphere, look for the constellation named the Southern Cross. It is on the South, so the opposite direction is North.
- Look for moss: More most grows on trees and other tall structures where there is less light. In the Northern Hemisphere, this is the north side of the tree. In the Southern Hemisphere, it is the south side of the tree.
Experiments Using Your Homemade Compass
There are many experiments that you can do using your homemade compass:
Map orientation: Use your compass to orient a map of your area. Try to find different landmarks on the map and navigate to them using your compass.
Magnetic fields: Explore the magnetic fields of different objects around your house. Try holding your compass near a refrigerator magnet or a speaker.
Magnetic declination: Look up the magnetic declination for your location. See if you can figure out how far off your compass is and the direction of the error.
Conclusion
Making a homemade compass is a fun and educational activity that you can do with your family or friends. It’s a great way to learn about the history of navigation and explore the principles of magnetism. With your homemade compass, you can explore your surroundings and discover new things about the world around you.
References
- Gade, Kenneth (2016). “The Seven Ways to Find Heading”. The Journal of Navigation. 69 (5): 955–970. doi:10.1017/S0373463316000096
- Gurney, Alan (2004) Compass: A Story of Exploration and Innovation, London : Norton, ISBN 0-393-32713-2.
- Lowrie, William (2007). Fundamentals of Geophysics. London: Cambridge University Press. ISBN 978-0-521-67596-3.
- Schmidl, Petra G. (2014). “Compass”. In Ibrahim Kalin (ed.). The Oxford Encyclopedia of Philosophy, Science, and Technology in Islam. Oxford University Press. ISBN 978-0-19-981257-8.