Planck's Constant from an LED

The objective of the experiment to experimentally measure Planck's constant using an LED light up using a known voltage and measuring the wavelengths of the diffracted light.

Procedure:
See Physics 4C Lab Manual (Martin Sydney Mason), "Planck's Constant from an LED."

Data and Observations

 

Analysis

 

Using a curve fit for the data, the equation is y=1480*10^-6x-0.455. To get Planck's constant, h, it is necessary to multiply by e (the charge of an electron) and divide by c (the speed of light). Doing so, the experimental value of h is 7.938*10^-31. 

Conclusion and Error Analysis

Since the accepted value of h is 6.626*10^-34 J*s, the percent error is 119700%, which is extremely high. This is mostly likely due to the sensitivity of the experiment of small, precise values. As shown in the graph above, the shape of the curve does not fit the slope of 1480*10^-6 very well.