كيلر سحق والفرز
Hertz Wikipedia. Definition. The hertz is defined as one cycle per second.The International Committee for Weights and Measures defined the second as "the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium-133 atom" and then adds: "It follows that the hyperfine splitting in the ground state of ...