To fully understand why magnets have two poles, (the north and south) instead of one, three, or more, you will first need to understand the basic concepts of the electron spin and its relationship with the Earth's cores. Even after we've compressed the answer we have, we're still unable to provide you with a short answer, so bear with me and read the article until the end to know exactly why.
Electron Spin and Magnet Fields
Charged particles that constantly move around create what is known as the magnetic field. This magnetic field will then exerts a type of force on other charged particles. Electrons possess a unique property known as electron spin, which causes a type of force to be exerted on them by the magnetic field. In reality, the electron spin is actually a quantum property, and it's analogous to the regular spinning of objects that we would usually observe in our everyday life.
They share some similarities, but there is a clear difference between an electron spin and the spinning motion of an object. However, we will not go in-depth about the difference between these two as we will be more focusing on why magnets have only two poles. What exactly happens inside of a magnet at an atomic level is that each electron in a particle spins to produce minute magnetic fields.
These micro magnetic fields produced by each electron will then be combined together to produce a stronger magnetic field that can affect other charged particles located far away. The magnetic force exerted by one particle will cause the other charged particles nearby to be influenced by the same magnetic force.
The magnetic force that is exerted on a particle with spin causes the particle to rotate its spin to adhere to the magnetic field of the other charged particles. Consequently, a small magnet located inside a bigger magnet will try to follow the magnetic field of the bigger magnet.
The Effect of Earth on Magnets Creating a North and South Pole
Metal is the primary material that can be found in the Earth's core. The Earth's core is made up of two main parts. The first part is the cool liquid external core, and the second part is the hot solid internal core. The difference in these temperatures results in currents in the liquid metal, just like how hot air rises exactly above the cool air.
We also need to keep in mind that Earth is also constantly spinning at the same time. Consequently, the liquid metal current will also spin due to the rotating motion of our planet. The final effect is to make a gigantic magnetic field that points somewhere in the northern regions.
By combining both of these ideas together, we would find that the magnetic field of the Earth will cause the magnets that we have on our hands to point from North to South. Do you still remember how a small magnet inside a bigger magnet will adhere to the magnetic field of the bigger magnet? The same concept applies in this case. This is the reason why people would label the poles of a magnet as North on one end and South on the other.
In a nutshell, the rotation of the Earth produces a giant magnetic field. The Earth's magnetic field greatly affects the polarity of smaller magnets available on the planet. This, in turn, causes magnets to have a North and South Pole.
However, at the same time, the magnetic field doesn't specify which direction is North or South. In fact, the polarity of the Earth's magnetic fields changes from time to time. This phenomenon occurs once every hundred years or so where the North pole switched place with the South pole.
We have this information because we observed the orientation of the magnetic materials located deep inside the ground. From this, we can observe how the polarity of the magnetic field changes as time passed.
You might wonder why most of the diagrams explaining a magnet's field lines visualize the arrow pointing outward at the North and inwards at the magnet's South poles. Well, the answer is simple. If you place the North pole of a magnet near the South pole of another magnet, both of these magnets will be attracted to each other.
The field lines visualized in most diagrams are derived from this particular observation. Hence, scientists concluded that the magnet's North pole field lines point outwards while the field lines at the South point inwards.
How to Determine Which Part of the Magnet is the North or South Pole?
- You may use any type of compass that you prefer in this activity. As for the magnet, it's highly recommended for you to use either a bar magnet or a disk magnet.
- Test your compass to make sure that it functions properly. In most cases, the red needle of the compass would usually point North while the blue one points towards South.
- In case you don't know the direction of your geographic North, you can always determine the North needle of your compass by going outside during noon, where the sun will be at the highest point in the sky.
- Place the compass as flat as you could on the palm of your hand. Make sure that the South needle points directly towards your body.
- Pay close attention to the position of the needles. If you're located somewhere in the North equator, the North needle of your compass should point towards your body and vice versa.
- After you've determined the direction of your North and South pole, place the compass on a table.
- Ensure that the table is not magnetized, and keep away any metal objects to prevent any false readings.
- Even simple objects such as a pocket knife and keychains could interfere with the reading of your compass.
- Place the magnet on the table. Bring your compass close to one end of your magnet to determine its polarity.
- Look at the needle of your compass. If the North needle of your compass point towards the magnet, this means that you have the South pole of the magnet and vice versa.
Can There Be a Magnet That Only Has One Pole North or South?
Currently, there's no magnet that only has one pole as all of the magnets in this world have a North and a South pole. So far, physicists are trying their best in the Large Hadron Collider (LHC) located in Geneva, Switzerland, to search for a magnetic monopole. However, up to this day, they have no concrete evidence that could prove the existence of a magnetic monopole.
However, scientists in London Centre for Nanotechnology (LCN) have recently discovered a piece of evidence that might be able to prove the existence of magnetic monopoles in nature. There are two papers that these scientists write that could help shed some light on magnetic monopoles.
A magnetic monopole is a magnetized version of a charged particle such as electrons that many scientists have tried to discover for the last 70 years. The magnetic monopoles that these scientists have discovered are not the ones that could change everything; rather, the ones that could provide us with some clues to the future of magnetic monopoles.
The magnetic monopoles that the scientists have discovered, instead of exists everywhere in the universe, could only be found in a special type of material known as thin ice. These magnetic monopoles can be visualized as the South and North poles of a magnet that is free to float anywhere within the thin ice.
The scientists in the LCN utilized a new type of neutron scattering method to map the world where the monopoles are currently living. All of these have been made possible thanks to the latest tweaks to the experimental instruments at the Institut Laue-Langevine (ILL). Furthermore, since ILL received many sponsorships from the UK government, they have managed to help scientists in LCN to boost the speed of their research and developments.
ISIS is another UK research facility responsible for the production of subatomic particles known as muons. These muons will then be used to act as a probe for the magnetic monopoles. Specifically, in this experiment, the scientists have successfully measured the charge of the monopoles, and they have found that it was the same as the one that was predicted theoretically.
Aside from providing huge positive impacts to the world of fundamental physics, these monopoles can be harnessed the same way as how electrical charges were harnessed in the past. However, discovering a magnetic version of electricity is still far from reality, but these recent discoveries surely provide us with a good start.
Magnets are complicated and there is still a lot we don't know about them. New research is being done and new information is constantly being discovered. As of now, there is no concrete evidence of a magnet with more or less than one pole, but there are scientific groups looking for clues of its existence. For now, all I can say is every magnet we've come across has a north and south pole and it all comes down to the magnetic field created by the earth and the effect it has on the smaller magnets found on the planet.