Due to its discrete nature, it led to a precise definition of the unit of electrical resistance, which was given the name of its discoverer.  It only 
Due to its discrete nature, it led to a precise definition of the unit of electrical resistance, which was given the name of its discoverer.  It only occurs in two-dimensional surfaces, which is why it is properly in the realm of semiconductor physics.  Its discoverer found the surprising fact that it was exactly discrete, namely that electrical conductance equals v times e-squared over h, where v is any integer, e is the fundamental charge, and h is Planck's constant.  The earlier form of it described the creation of a voltage in the direction perpendicular to a magnetic field applied to a perpendicular current and offered an interpretation of current, rather than as a movement of negatively-charged electrons, as a movement of positively-charged "holes".  FTP, identify this effect for which Klaus von Klitzing won the 1985 Nobel Prize in Physics.
Due to its discrete nature, it led to a precise definition of the unit of electrical resistance, which was given the name of its discoverer.  
quantum Hall effect or quantized Hall effect (do not accept or prompt on "Hall effect")