The washers make it heavier, so the force of gravity pulls it down, and the magnetic field pulls it up.
The world’s strongest magnet is capable of sucking in objects, generating electric current, and levitating non-magnetic objects. It can even wreak havoc on camera equipment, as wire is magnetic! If it’s a CMOS sensor, the electrons are redirected, making it difficult to shoot in these magnetic fields.
This magnet is located at the National High Magnetic Field Laboratory in Tallahassee, Florida, and can create a magnetic field of 45 Tesla, nearly a million times Earth’s magnetic field. It consists of an outer superconducting magnet and an inner resistive magnet. This magnetic field extends past the magnet, known as the fringe field, although it is much weaker than 45 Tesla. It is still dangerous, as objects with shapes will start orienting themselves to the field.
Ramping up this magnet to full power takes around an hour and a half, as they have to put 47,000 amps of current into the outer superconducting electromagnet. This magnet is so powerful that it can attract magnetic materials, as demonstrated by putting steel washers into a Nerf football, making it heavier and being pulled up by the magnetic field. I tried to throw the football and hit the side of the magnet. After a few misses, I realized that it bounced around and stuck. Another thing to do if you have a strong magnet is get ferrofluid fluid. This fluid contains nanoscale pieces of magnetite, an iron containing mineral, and when exposed to an external magnetic field, they line up like iron filings around a bar magnet. This fluid can even form parallel ridges meters away from the magnet. As you get closer, spikes form on the surface, aligning the magnetite particles with the field. Magnetite is the mineral that led people to discover the phenomenon of magnetism in the first place and it was discovered that lodestones (naturally magnetized pieces of magnetite) could attract each other or pieces of iron. In the powerful magnetic field around the world’s strongest magnet, even non-ferromagnetic materials can be affected. When they are stationary in the field, there’s no difference between them, but when they move, materials that conduct electricity fall a lot slower. This portion of the video was sponsored by Google, as they are interested in magnets which are core to our future such as electric vehicles. According to Google Trends, search interest for electric vehicles has reached an all-time high in the last 12 months. (metal clanks)
People are trying to find ways of doing things that are less destructive to the planet and Google is taking part in this effort. Since 2017, Google has matched 100% of their electricity use with renewable energy and they run Project Sunroof which helps people decide if solar is right for their home. Lenz’s Law, also known as the “No You Don’t” Law, states that whatever you try to do, nature acts to oppose you. This can be seen in the example of dropping a plate towards a north magnetic pole. The induced currents create a north magnetic pole themselves so that the plate is repelled and falls much slower. We also tried a number of other conductive objects around the magnet and found that no matter what we tried, nature said “No You Don’t”. Finally, we fired projectiles from a potato cannon across the top of a 45 Tesla magnet and saw that the induced eddy currents rotated the projectile so that it remained oriented along the magnetic field lines. To learn more about sustainability and Google’s efforts, visit sustainability.google. The projectiles contain coils of wire connected to LEDs, so no matter which direction the field is coming in, one of them will be lit. When the projectiles cross through a field, the change in color of the LED of the nose cone can be seen.
In all these cases, the induced electric energy is dissipated either as light or heat, but if a material like a superconductor below its critical temperature is used, then most of the material has zero electrical resistance. This means that if a magnet is brought close to it, currents will be induced to oppose the change in flux and since it’s a superconductor, those currents can persist indefinitely and expel all of the magnetic field.
The human levitator consists of a magnet hovering above a ring of superconductors. When someone stands on the magnet, it is pressed down into the superconductors, creating a magnetic flux that is opposed by currents in the superconductors, creating a magnetic field that repels the magnetic field from the magnet.
Some materials are always attracted to magnetic fields and display what’s called paramagnetism. Oxygen is an example of this. Other materials, such as water, are repelled by a strong enough magnetic field and this is known as diamagnetism. In a strong enough magnetic field, even a strawberry can be levitated. Wow! People have actually levitated frogs and grasshoppers in experiments to study the effects of weightlessness without having to go into space. Is it safe for living things to be exposed to strong magnetic fields?
Yes, there are no lasting or long-term effects. However, there is the possibility of polarizing the stones in the inner ear of rodents, which causes them to spin in circles for a few minutes after the exposure to the magnet.
So how do you make the world’s strongest magnet? It turns out that superconducting magnets alone cannot achieve the highest magnetic field. The solution is to combine an outer superconducting electromagnet with an inner electromagnet made of ordinary wire, which can produce up to 45 Tesla. This is done by using a helix-shaped conductor that allows cooling water to be pushed axially through the stack of conductor.
Running the strongest magnets on the planet requires a lot of energy. The Mag Lab uses around 8% of Tallahassee’s electricity when all four power supplies are running at full blast. So nominal $250 to $300,000 a month is the electricity budget of this place. Holy, yeah, that’s a lot. This is because they operate in a federally mandated reserve, which every utility has to have and be able to push into the grid in case of problems. They have a deal set up with the city so that they can make money off the power that they have to produce but cannot sell. On the other hand, when they need it, they can ramp down faster than spinning up a Genny.
The 45 Tesla is needed for a couple of reasons. One is for growing a new material and the other is for putting it in an extreme environment like a high magnetic field, high electric field, high pressure, or ultra low temperature. Another reason is for improving the cleanliness of an existing material by getting rid of all the impurities. This enables people to see things that were never seen before. People will look back 25 years from now and see this five year period as the inflection point.