User:David J Weiss/Notebook/people/weiss/Photoelectric
Summary of the Photoelectric Effect Lab
In this lab we tried to find the value for Planck's Constant (h). This was accomplished by shining a light produced by stimulating mercury gas to get the different spectral lines and directing these lines at a photo diode and measuring the different stopping potentials and times to get the equation of a line, which we would then use to find h.
During this process we encountered several difficulties from day to day. These difficulties were quite frustrating and caused the data to differ from day to day which was a pain and quite discouraging. The reasons for this I could not quite figure out. SJK 17:30, 25 October 2009 (EDT)
I think actually your data were better than you thought. It's possible you got hung up worrying about the 3rd digits of the voltage, when actually the fluctuations weren't always important? My best guess is that your frustration prevented you from thinking clearly about the analysis. Problems are noted on your primary notebook page.
The average value of h that I got was [math]\displaystyle{ h_{average}\simeq 6.02\times 10^{-34} Js }[/math] i got this by taking the h of the first order and adding the h of the second order and dividing by 2. The value I got for [math]\displaystyle{ W_0 }[/math] was [math]\displaystyle{ W_{0 average}\simeq -3.58\times 10^{-19} J }[/math]
An accepted value for Plamck's Constant is [math]\displaystyle{ h_{accepted}=6.62606896(33)\times10^{-34} Js }[/math] from Wikipedia which would make my error
- [math]\displaystyle{ \% error=\frac{h_{accepted}-h_{measured}}{h_{accepted}}=\frac{6.62606896(33)\times10^{-34} Js-6.02\times 10^{-34} Js}{6.62606896(33)\times10^{-34} Js}\simeq 9.06 \%\,\! }[/math]. This would make this an OK experimental result but i would not trust it that much due to the fact that the 1st order was an extreme undershot and the 2nd order was and overshot and the average was also a little off. But what can you do in the end.
