Materials that have no resistance to currents of electricity are known as superconductors and are considered to be one of the last of the greatest scientific discoveries. As the upper limits of superconductors have yet to be found, theories regarding their behavior are constantly being tested.
In the year 1933 two German researchers named Walther Meissner and Robert Ochsenfeld found out that a material that is a superconductor will repel a magnetic field. A magnet operated by the force of a conductor will cause currents in the conductor, which is the basis on which the electric generator was founded. But with superconductors the induced currents perfectly reflect the field that would otherwise have gone through the superconductive metal, which thereby causes the magnet to be repelled. This scientific process is known as strong diamagnetism and today is known as the Meisser effect. This phenomenon is so powerful that a magnet can be levitated over any kind of materials that have superconductivity properties.
Other than the well-known Maglev trains which use superconductors to levitate trains above magnetic rails, other uses of superconductors are MRI (magnetic resonance imaging) machines, particle accelerators and fast electronic switches.
There are two types of superconductors, type I and type II. There are thirty Type I materials that show signs of zero resistance at low temperatures and have the ability to give off magnetic fields from inside the superconductor. Their superconductivity properties only exist below their critical temperatures and below a certain magnetic field strength.
Type II superconductors are mechanically sturdier than their Type I counterparts. Type II materials also give off significantly higher critical magnetic fields. Materials with Type II conductivity like niobium-titanium are utilized in the construction of high field superconducting magnets. Materials with Type II superconductivity exist in a blended state between normal and superconducting regions, which is called a vortex state because vortices of superconducting currents circle cores or filaments of normal materials.