Which Pole Is North?

1. What is a Magnetic Pole?

Every magnet has both a north and a south pole. There are no magnets with only one pole. See magnetic monopoles for more details. With an axially magnetized disc magnet, for example, you could write a big N and an S on either round face with a marker. The question is, which is which?

Often times, the poles are often referred to as being positive or negative. Generally, the south pole is termed positive, and the north negative. This terminology probably stems from trying to model the H-field as analogous to an electric E-field of positive charges, which works under some circumstances.

2. Magnetic pole identifiers

Many magnets do not have their poles marked and a magnetic pole identifier is a quick and easy way to find which side of a magnet is the north or south pole. Some magnets like blocks and discs can be magnetized in multiple directions making it even harder to identify which side is north. We offer several types of pole identifiers to take the guesswork out of this process.

Pole identifiers we offer:

1. Electronic magnetic pole identifier

   The simplest to use is the electronic pole finder. Simply point the tip at one side of the magnet, press the button, and an LED will light to indicate the polarity, north or south. On a production line, this is your best bet. It works well, consistently, and avoids any confusion.

2. Marked cylinder magnet pole finder

   A less expensive option is the D4X0-ND magnet. It has a small dimple on the north end of the cylinder, and can be used to identify the poles on unmarked magnets. The north pole of one magnet will be attracted to the south pole of another -- just remember that opposites attract!

3. Red and black plastic coated pole finder

   We recently introduced the two-color, plastic coated D68PC-RB magnets. These cylinder magnets are red on the north pole and black on the south. They've become our new favorite pole-identifying magnet.

   The plastic coating makes it more durable, and won't tend to scratch another magnet. When identifying the pole on larger magnets, this is especially good news.

3. How to identify the north pole of a magnet

There are many ways you can find which pole is north or south on your magnet, but we have listed some of the top ways below:

1. Using an electronic pole finder

   Our EPID2 electronic pole identifier is the best way to find a magnet's pole. Simply point the tip at the magnet and a light will indicate whether it is the north or south pole. This is also convenient because it will not attract to the magnet and does not require other tools or setup to work.

   

2. Using another marked magnet

   Our D4X0-ND cylinder magnet with a dimple at the north pole has long been a favorite of ours. It is a simple tool for identifying the north pole of another neodymium magnet.

   The plastic coated D68PC-RB is also a good choice and the red and black colors make it easier for identifying poles. The plastic coating also adds impact resistance and is less likely to scratch surfaces.

   

   

3. Using a a compass

   What about using a regular compass that you might have on-hand to identify the poles of your magnets? Remembering which end of the compass points to which pole of the magnet can be confusing. It is easy to get mixed up. As described in our article, The Earth Is a Magnet, the earth is a big magnet with the magnetic south pole actually located in the north (in northern Canada, currently).

   The labeled pictures below should be a good guide to using a compass to identify the poles of your magnets. See the descriptions. Or, remember that they're pointing in the same direction.

   Sphere compass

   The first compass we used was an inexpensive, sphere-shaped compass actually uses a neodymium magnet inside.

   

   

   Round compass

   The second compass we used was a traditional needle compass that uses a piece of magnetized steel. Be careful to avoid getting a neodymium magnet too close to this second type of compass. The powerful magnetic field of a neodymium magnet could demagnetize the needle, or even magnetize it in the opposite direction!

   

   

4. Top 3 ways to make your own compass using magnets

1. Magnets on a string compass

   If you don't have a pole identifier readily available, you can use a little science to find the north pole of your magnets. Your magnet's north pole is attracted to the Earth's north pole. Technically, the Earth is labeled backwards -- the magnetic pole near the geographic north pole is actually like the magnetic south pole of a magnet.

   If you hang a small stack of magnets on a long thread, the magnets will freely rotate. Hang up your 3 foot length of string on a stable platform, like an overhead light. Once it stops wobbling, the north end should be pointing north. If you know roughly which direction is north (the sun rises in the East), you'll find your magnet's north pole.

   

2. Floating magnet compass

   A great science project is to create a compass by floating a magnet on piece of Styrofoam. The lightweight, floating platform gives the magnet a nearly frictionless surface to freely rotate on. The north pole quickly becomes obvious -- plus it's neat to experiment with! This floating compass is a great science project idea for kids. Be sure to include adult supervision with strong magnets.

   

3. Magnet on edge as a compass

   Less interesting to build, but super simple: You can place a disc magnet on it's edge on a smooth surface. If your magnet is sized right to balance this way, it will twist to point north. Simple, but effective.