Since i managed to mess up a bit in my last superconductor article by claiming that superconductors would bring the holy grail of quiet laptops to the world (I’m still sad i was wrong, mostly because my laptop is loud as hell), I figured I’d try and redeem myself with a bit by writing about superconductors some more. Although my grade in solid-state physics suggests that i will make another gaffe here.

In the last article i just kinda sprung the picture of a magnet being levitated on you, mostly because it looked cool and, i know that at least I am too simple to ever read anything without pictures. But it is in fact a demonstration of a remarkable effect that superconductors have. Check out the video for a more dynamic demonstration of it.

It’s called the Meissner effect, and it basically means that if you have a sample, and you cool it down to superconduct, it will expel all magnetic fields fields out (meaning that there is no magnetic field inside a superconductor). In technical terms, this means that superconductors are perfect diamagnets. A diamagnet is basically something that if put inside a magnetic field, it will create a new magnetic field that points in the opposite direction of the original magnetic field. This allows for fun things such as levitating frogs. A frog only creates a very small opposite magnetic field, however a perfect diamagnet, like a supercondutor is, would create the exact same field as it was experiencing, in the opposite direction.

Ok that’s all probably a bit confusing, with me saying “Magnetic” 10 times in one paragraph, so I’ll take it step by step, here’s what’s happening:

1) You cool a material down far enough so that it becomes a superconductor.

2) You place a normal magnet on top of the superconductor, this makes the superconductor feel a magnetic field, that we will call B.

3) The superconductor wants to have zero magnetic field inside itself, and so it creates a magnetic field (created by moving electrons), that is exactly enough to cancel out B inside the conductor.

4) The field created by the superconductor now interacts with the magnet and is strong enough to counteract gravity and levitate it.

Bonus video! A frog being levitated. It’s the same principle, BUT the frog is not a perfect diamagnet, so you need a VERY high magnetic field for it to create a strong enough opposite magnetic field to overcome gravity. Note that in this video the diamagnet and the magnet have switched places. Before the diamagnet was on bottom (the superconductor) and the magnet was being levitated, now the magnet is on bottom, and the diamagnet (the frog) is being levitated.