Study of Plancks Constant by means of LED

Country of Origin

Made in India

Several proposals to measure the Planck’s Constantfor didactical purposes, using the current-voltage (IV) characteristics of a light emitting diode (LED) have been made quite regularly in the last few years. The physical interpretation however is not completely clear and this has raised many discussions, which have been published almost with same regularity as the proposals themselves. I=I exp [-e(V -V)/ hkT] Where, e is electronic charge, k is Boltzmann constant, T is absolute temperature and h is material constant which depends on the type of diode, thelocation of recombination region, etc.i) Dependence of current (I) on temperature (T)at constant applied voltage (V)The following facilities are built in for thisCurrent Meter : • A highly stable current source with 3½ digitdisplay.• Range : 0-2μAwith resolution of 1 μAOven, PCO-01• It is a small temperature controlled oven withbuilt-in RTD sensor.• Temperature adjustable from ambient to 338K• Digital display of temperature• High stability 1KVariable Voltage Source (0-2V)• A high stability voltage source with 3½ digitdisplayii). Material ConstantTo draw I-V characteristics of LED fordetermination of h, a variable voltage source and acurrent meter are provided with 3½ digit displayiii) The wavelength l of light emitted by LEDThese are taken from LED datasheet or measuredby a transmission grating, and are provided withthe set of LED’s