Chances are you've ever heard the following phrase: "Opposites attract." While this cliché may not be the best advice when it comes to relationships, it is the general rule of thumb for determining the polarity of a magnet. Because humans inhabit a gigantic magnet (which is planet Earth), understanding the polarity of a small-scale magnet will help you understand the larger magnetic field that protects us from space radiation. If you want to label your magnets for future use or just want to do a fun science experiment, here are some easy methods to determine the polarity of your magnets.
Method 1 of 3: Use a Compass
Step 1. Gather your supplies
You only need a compass and a magnet. You can use any type of compass, but the simplest type of magnet for this method should be a ring or bar magnet.
Step 2. Test the compass
On a normal compass, the needle that points north is usually the red one. However, it is better that you always check this detail. If you know where north is located geographically from your current location, you can easily see the end of the compass needle pointing in that direction.
- If you are not sure where geographic north is located, you can go out at noon (when the sun is highest in the sky) to determine the north end of the needle. You should hold the compass flat in your hand with the southern end closest to your body.
- Observe the position of the compass needle. If you live north of Earth's equator, the north end of the needle should point toward you and the south end toward the sun. If you live south of the Earth's equator, the south end of the needle should point toward you.
Step 3. Place the compass on a flat surface (like a table)
Make sure the surface is free of magnetic or metallic materials that can cause an erroneous reading. Even certain objects (such as key chains or knives) can interfere with the experiment. You will notice that the north end of the needle points to your geographic north.
Step 4. Place the magnet on the table
If you are using a ring magnet, the north and south poles should be on the two flat surfaces. If you are using a bar magnet, the poles should meet on both ends.
Step 5. Place the magnet next to the compass
If you are going to use the ring magnet, you have to place it on its side and hold it with your index finger so that one of the flat sides points towards the compass.
If you are using a bar magnet, you should place it perpendicular to the compass so that one end of the magnet is close to the compass
Step 6. Look at the compass needle
Because the needle is a small magnet, the south end will be attracted to the north pole of the magnet.
If the north end of the needle points towards the magnet, then you have found the south pole of the magnet. Turn the other side of the magnet toward the compass. The south end of the needle should now point directly to the north pole of the magnet
Method 2 of 3: Create a Compass with a Bar Magnet
Step 1. Find a piece of string
You can use any type of string that you find around your house (for example, a piece of yarn or a ribbon for wrapping gifts). The string should be long enough to wrap around the magnet and suspend it.
A rope of approximately one meter is considered adequate for most cases. You can calculate this measurement by holding the string with both hands. With your right hand, hold the string over your nose. Then extend your left arm as far as you can. The length of the rope between the left and the right hand is almost one meter
Step 2. Tie the string tightly around the bar magnet
You must make sure that the rope is well tied so that the magnet does not slip through the knot. Note that this method is not the most appropriate if you have a ring magnet or a magnetic sphere.
Step 3. Keep the rope away from your body
Make sure the magnet can rotate freely without coming into contact with any impediment. As soon as it stops rotating, the end pointing north will be the north pole of the magnet. Congratulations! You just created a compass.
Notice the differences with the compass method, in which the south end of the needle is drawn toward the north pole of the magnet. When using a magnet as a compass, the north pole of the magnet must point north. What we know as the north pole should be called the "north-seeking pole", to be more precise, since it is attracted by the south pole of the planet's internal magnet
Method 3 of 3: Float a Magnet
Step 1. Gather your supplies
This method requires some basic household products that you probably have on hand. If you have a small magnet, a piece of Styrofoam, water, and a container, you can develop a fun experiment that will help you determine the polarity of your magnets.
Step 2. Fill a cup, bowl, or small plate with water
You don't need to fill the container completely, just enough so that the Styrofoam can float freely.
Step 3. Prepare the Styrofoam
This product should be small enough to reach into the container, but not so small that it can hold the magnet. If you have a very large piece of styrofoam, you can cut it a little so that it fits into the container.
Step 4. Place the magnet on the styrofoam
The styrofoam pad should rotate until the north pole of the magnet points north.
- If you need to check the polarity of the magnet regularly, you can purchase a magnetic pole detector to determine them without much effort.
- You can use any magnet, the poles of which you have already determined, to help you determine the polarity of another magnet. The south pole of one magnet must join the north pole of the other.