Determination of Plancks constant from the LED

Determination of Plancks constant from the LED

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Product Description

Study of Planck’s Constant by means of LED

Several proposals to measure the Planck’s Constant for didactical purposes, using the current-voltage (I-V) 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, the location of recombination region, etc.

1) Dependence of current (I) on temperature (T) at constant applied voltage (V)
The following facilities are built in for this
Current Meter
• A highly stable current source with 3½ digit display.
• Range : 0-2000µA/ 20mA


• It is a small temperature controlled oven with built-in RTD sensor.

• Temperature adjustable from ambient to 80 degree celcius
• Digital display of temperature
• High stability
Variable Voltage Source (0-2.75V)
• A high stability voltage source with 3½ digit display

2). Material Constant
To draw I-V characteristics of LED for determination of h, a variable voltage source and a current meter are provided with 3½ digit display.

3) The wavelength l of light emitted by LED
These are taken from LED datasheet 


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