von Klitzing constant
von Klitzing constant[fȯn ′klit·siŋ ‚kän·stənt]
The quantity RK = h / e 2, where h is Planck's constant and e is the charge of the electron; materials that exhibit the quantum Hall effect have a Hall resistance equal to RK / n, where n is either an integer or a rational fraction. Also known as quantized Hall resistance.
The conventional value of this quantity adopted by international agreement on January 1, 1990, to establish a standard for the ohm, RK- 90 = 25,812.807 ohms.