5410 Planck's constant measurement kit

The measurement of Plack’s constant can be obtained also exploiting the quantum properties of the LED diodes. If a LED diode is directly polarized, it starts emitting light the moment the potential energy eVs, produced by the electrons, is enough to make them pass from the conduction band to the valence band (Energy gap). As consequence of this energy gap , every electron emits one photon of energy.

hf = eVs

If you know the potential Vs in correspondence of which the LED starts emitting a weak light , it is possible to go back to the value of h. 3 LED are supplied, red green and blue, in order to verify that the higher the energy gap is, the more intense the emitted light frequency becomes.