Planck's Constant from an LED

6.6262*10^-34 the value for planck's constant, we know that from the book and have used it millions of times, but to solve for where it came from, that when LED and color spectra comes in to place.





LEDs or A light-emitting diode  is a semiconductor light source. LEDs are used as indicator lamps in many devices and are increasingly used for other lighting. 


when using different colored LEDs we can find the spectra on where these LED hits and from the color and spectra equation we relate the wavelength to the amount of eVs that is being emitted. 


we had four different types of color

	Distance D (meters)	Voltage (Volts)	Wavelength (nm)
Yellow	0.65	1.92	590.43
Green	0.54	2.56	535.04
Red	0.75	1.79	660.93
Blue	0.532	2.61	445.76

with the values of waves length known, we can easily show that
E = hc/lambda = q_eV


since we know the charge of the electron the voltage 3V, and lamba and c are known values as well we can solve for planck's constant


the closes result we got from those wavelength was red which gave an vault of  6.23*10^-34 which is about right on the vault of planck's constant.


for the other vaules of h that we got it was anywhere going from a 1.6% error to about 10% error, this could have been measuring errors due to estimating and round off numbers. also when reading the color spectra it was hard to determine the center point of the spread, this might also affect the value of h found by the other wavelengths