Archive | Electricity and Magnetism RSS feed for this section


24 Oct

This is pretty amazing. Let me tell you a bit about what is going on here. Superconductors do not like magnetic fields. If possible, the superconductor will expel the magnetic field from its interior. This is called the Meissner Effect. But in this case, the superconductor is a super-thin wafer of ceramic on top of a sapphire substrate. It is so thin that the magnetic field does penetrate the superconductor, but in discreet quantities called flux tubes. The flux tubes penetrate weaknesses in the superconductor, like grain boundaries. Any spacial movement of the superconductor would change the position of the flux tubes. The flux tubes really want to stay in the grain boundaries, so the entire superconductor is locked in place. Strongly.

Image courtesy of Tel-Aviv University


Biggest magnetic field ever

26 Sep

Here’s a fun one. German scientists have made a magnetic field of 91.4 T. That is BIG! The earth’s magnetic field is between 30 and 60 microTesla (says Wikipedia). That means it’s between 0.000030 and 0.000060 Tesla. The magnetic field they created is a millions times that of the earth’s magnetic field at the surface of the earth.

Honestly, it’s just a huge wrapping of copper coil inside another huge wrapping of copper coil… you get the idea. Flowing electrical current creates a magnetic field around itself, so line up a bunch of currents and you can create a magnet. The big one was tricky to engineer, though, because the windings would normally tear themselves apart at about 25 Tesla. Big magnets are good for researching superconductors, etc very accurately. Read more here.