FTP, name this effect that describes the expulsion of a magnetic field from the interior of a material when cooled below the transition temperature.
It was discovered in 1933 by Ochsenfeld and its namesake.  Type I superconductors, like tin and mercury, can be made to exhibit this completely by eliminating various chemical impurities and by choosing proper geometrical shape and size.  Type II superconductors, like vanadium and niobium, exhibit this only partially at intermediate magnetic field strengths, regardless of geometrical shape and size.  FTP, name this effect that describes the expulsion of a magnetic field from the interior of a material when cooled below the transition temperature.
It was discovered in 1933 by Ochsenfeld and its namesake.  Type I superconductors, like tin and mercury, can be made to exhibit this completely by eliminating various chemical impurities and by choosing proper geometrical shape and size.  
Meissner effect