How does a Superconductor Work?
In order to understand how a superconductor works, it may be helpful to examine how a regular conductor works first. Certain materials such as water and metal allow electrons to flow through them fairly easily, like water through a garden hose. Other materials, such as wood and plastic do not allow electrons to flow through, so they are considered non-conducting. Trying to run electricity through them would be like trying to run water through a brick. Even among the materials considered conductive, there can be vast differences in how much electricity can actually pass through. In electrical terms, this is called resistance. Almost all normal conductors of electricity have some resistance because they have atoms of their own, which block or absorb the electrons as they pass through the wire, water or other material. A little resistance may be useful to keep the electrical flow under control, but it can also be inefficient and wasteful. A superconductor takes the idea of resistance and
In 1933 it was determined by Walter Meissner and Robert Ochsenfeld that superconductive materials can repel magnetic fields. They determined that when a material was penetrated with a magnetic field, in its’ superconductive state, it would create a current inside the superconductor. Because there is almost zero resistance in the material at its’ Tc temperature, the current creates an opposing magnetic field that exactly balances the originating field. When the material’s temperature becomes higher than its’ Tc value the magnetic field simply pass through it. This was an extraordinary discovery and thus the term “Meissner Effect” was coined to describe this unexpected occurrence. Ceramic superconductors have made it considerably easier to view the Meissner Effect due to their higher Tc values.
