Apparatus :
A. 0-10 V power supply
B. Digital milliammeter
C. Digital voltmeter
D. Known wavelength LED’s (Light-Emitting Diodes).

Procedure in laboratory (diagram)






Procedure in laboratory :

Prepare a circuit as per follows


























Analysis :
A) Determine the Knee voltage for Red, Yellow, Green and Blue LEDs
B) Note down the wavelengths for Red, Yellow, Green and Blue LEDs
C) Calculate the value of Planck’s constant