Throughout the years humans have used a number of methods to find their way (that is, to navigate) to their intended destination x. Hundreds of years ago people would use known landmarks, or the position of the sun, moon, and stars to decipher where they were. Beginning about the year 1040 AD, the Chinese began using the compass for navigation1. A compass (in this case, a magnetic compass) is simply a small magnetized needle or bar which is balanced on a point on which it can easily pivot or spin. This magnetized needle will pivot on this point such that one end of the needle points toward North. Generally this end of the needle is painted red, or otherwise indicates to the user which way is North. Using this simple device, human beings of the ancient world were able to cross oceans and continents, and .find their way home again.
Here’s what you’ll need:
1. A needle or other thin, lightweight piece of steel
2. A Styrofoam cup
3. A scissors
4. A glass pie plate
5. A strong bar magnet (good ones are available from eBay and Amazon.com, but you can always try your local hardware store)
Here’s what to do:
1. Fill the pie plate with water from your kitchen sink. Place the plate on a flat surface.
2. Carefully cut the bottom off the Styrofoam cup using your scissors. Be sure not to leave any of the cup edges.
3. Magnetize your needle: take the strong bar magnet and rub one end of it along the needle in only one direction at least 20 times. This will align the atoms in the needle, causing it to become magnetized. You can check to make sure your needle is magnetized using a few paper clips; if the needle will pick up the paper clips, it’s magnetized!
What did you observe? Did your needle point North? Did it stay this way? Be sure to write down all your observations!
CHALLENGE YOUR FRIENDS TO A TREASURE HUNT!
Hide a flag in a tree or in some tall grass. Make up a map to the object telling your friends how many feet or steps North, South, East, or West they should go from where they start. Then provide them with all the things they need to make their own compass to figure out which way is North! This works when the area is not very familiar, so going to a State Park or wooded campground would likely be a good location.
References for further reading:
1. Lowrie, W., Fundamentals of Geophysics. 2nd ed.; Cambridge University Press: Cambridge; New York, 2007.
2. Brain, Marshall. "How Compasses Work" 01 April 2000. HowStuffWorks.com. <http://adventure.howstuffworks.com/outdoor-activities/hiking/compass.htm> 28 May 2014.