What Is a Magnetic Field?
Magnets are fascinating things. They can be very useful in a wide range of practical applications, while they are also a lot of fun simply as toys. They are used in heavy industry, and they are also used in some of the most advanced scientific experiments mankind has ever taken part in.
What actually makes magnets and magnetic fields work is a difficult question to answer. To get close to the answers we need to dig deep into the world of quantum mechanics. We do have a reasonable understanding of them, however, and this is what we have learned so far about them.
1. Magnets
Weve all seen and/or used them, you may even have one stuck on your refrigerator, but what are they exactly? Electricity and magnetism are essentially the same thing, in much the same way that energy and matter are essentially the same thing. Atoms within objects are electrically charged, with negatively charged particles being attracted to positively charged particles. The atoms inside any material, such as a lump of iron, have electrons orbiting the nucleus. Atoms with unpaired electrons give that atom an electric charge, and this charge causes other nearby atoms to become aligned with them. When all of the atoms are aligned in this way, the object itself becomes magnetized.
2. Special Relativity
Electro magnets work thanks to special relativity as was described by none other than Alfred Einstein. Usually, the positively charged protons and the negatively charged electrons in a wire will cancel each other out. This all changes when an electric charge is passed through the wire, however, because the electrons then start moving.
The theory of relativity means that because the electrons are moving in relation to the protons, the distance between each of the electrons decreases to anything that is outside of the wire. With more negatively charged electrons, the wire becomes electrically charged, and the wire becomes magnetized.
3. Magnetic Fields
Magnets are somewhat of a mystery. We know that a magnet will emit a magnetic field around itself but we don’t really know why. We also know that the field can become magnified the stronger the magnet is but, again, we are not sure why.
The magnet emits a field around itself, meaning if two magnets come into contact with each others field then they will be attracted or repelled to each other according to which of the two magnets fields are facing each other.
4. Lodestone
Most of the magnets we use today have been magnetized deliberately by people. Using increasingly advanced technology, we have been able to produce increasingly powerful magnets that can be used in heavy industry and a range of other fields. The first magnets used by man were not manmade at all but were naturally occurring.
A lodestone is a piece of the magnetite mineral that has been naturally magnetized. The word lodestone means “leading stone” or “course stone” in middle English and was named as such because they were used in early magnets. Few other materials are natural magnets as lodestone is.
5. Our Planet
At the center of our planet is a solid core of iron and nickel. Surrounding this is a hot, molten area of iron and nickel that is constantly swirling around the solid core. This movement of the electrons in the molten core rotating around the solid core results in an electrical charge, and this causes the core to become a giant magnet.
As with other magnets, the magnet at the center of our planet will generate a magnetic field. This magnetic field is so large that it can be experienced on the surface of our planet. It also produces a north pole and a south pole.
6. Aurora Borealis
As mentioned, our planet has its own magnetic field, and you can even see this sometimes in one of the most magnificent sights of all: the aurora borealis. Every now and then, a solar flare will send electrons and protons hurtling toward Earth.
These are usually deflected by our planets magnetic field, but because the field is weaker at the poles, some of these electrons and protons will make it through to our atmosphere. When this happens, the collision of these particles with our atmosphere makes for the most stunning light display you are likely to see. These electrically charged solar winds would otherwise be enough to knock out our electrical grids, demonstrating how important Earths magnetic field is to us.
7. Navigation
Humans have been using compasses to navigate for a very long time. They can be trusted to point to true north no matter where you are in the world, and this is very valuable when it comes to getting your bearings. Other animals also use Earths magnetic field, but they don’t have compasses, at least not in the same way that we do.
Some species of birds, whales, turtles, and bees are able to detect the magnetic field and use it to navigate with. This is especially useful for animals that venture out and need to find their way back, and those that spend time in vast habitats such as oceans. It is not known how they do this, but it is thought that some animals have certain receptors that allow them to “see” the field.
8. The Worlds Most Powerful Magnet
Some magnets are more powerful than others. The most powerful on our planet is a manmade magnet that is found in the National High Magnetic Field Laboratory in Florida. It is 22 feet tall, weighs 34 tons, and produces a magnetic field of 45 Teslas.
This makes it approximately 2-million times stronger than the type of magnet you will find holding up your kids drawings on the fridge. It is also 10 times stronger than an MRI machine. Magnets of this strength are generally used for science experiments that help us to understand the workings of our universe better.
9. The Universes Most Powerful Magnet
The most powerful magnet that we know of is the Soft Gamma Repeater 1806-20. You won’t see this magnet anywhere on Earth because it is a kind of star known as a magnetic neutron star, or magnetar. It has a magnetic field of 100 billion Teslas.
For comparison, our entire planets magnetic field measures in at only 0.00005 of a single Tesla. For some perspective, that is enough magnetism to slow down a speeding locomotive from a distance of around a quarter of a million miles away. Only 10 of these objects have been discovered in the universe so far.
10. CERN
Magnetic fields are also in what is the worlds largest and most advanced scientific experiment: the Large Hadron Collider at CERN. The fascinating experiment helps scientists to smash apart the smallest particles that we know of to see what they are made of. The experiment has helped us to advance our understanding of the universe and helped us to discover the famous Higgs boson particle.
The experiment works by taking particles and forcing them round a huge circuit at just under the speed of light. Separate beams of these particles are sent in opposite directions to cause them to collide with each other. Powerful magnets are needed to help ensure the particles remain on the right course as they travel along the circuit.
