Physics307L:People/Klimov/Photoelectric: Difference between revisions
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* While I believe that we gathered data | * While I believe that we gathered data well, given its nearly perfect linear fit, or measured Plank constant was clearly inconsistent with the accepted value. Our best measurement lies roughly four and a half standard deviations away from the accepted value (>99.99% confidence interval). | ||
* I believe that systematic error prevailed in this lab, which could have been caused by several factors. | * I believe that systematic error prevailed in this lab, which could have been caused by several factors. As I discuss in my lab notebook, there is a chance that fringe overlaps or charge leaks could have caused us to obtain erroneous measurements for the stopping potential. However, a definitive solution was not discovered, and so the problem is still unresolved. | ||
* If I had more time to explore the photon theory of light and the photoelectric effect, there is one thing that I would like to try -- I would like to build my own photoelectric effect apparatus. This way I would not have to question the accuracy of the black-box, which is inevitable, given that it automatically spits out the voltage readings. | |||
Revision as of 20:11, 9 November 2008
Planks Constant
The photoelectric effect is an important experiment in the history of physics because it clearly displays the quantum theory of light. The photoelectric effect describes the emission of photoelectrons due to the absorption of light quanta, photons. According to Einstein's theory, each photon carries a certain amount of energy that is proportional to the frequency of light (not intensity, as in classical theory). The proportionality constant is the famous Plank constant. In this lab, we set out to find the value of this constant by measuring the stopping potential of a circuit, whose current is 'generated' by photoelectrons. In addition to measuring the Plank constant, this method also allows one to measure the work function of the metal.
Important Links
Data
[math]\displaystyle{ h_{meas} = 7.26(14)\cdot 10^{-34} J \cdot s }[/math]
[math]\displaystyle{ h_{act} = 6.626\cdot 10^{-34} J \cdot s }[/math]
[math]\displaystyle{ W_{meas} =1.635(48)\cdot eV }[/math]
[math]\displaystyle{ W_{act} = 1.36(8) \cdot eV }[/math]
Conclusions
- While I believe that we gathered data well, given its nearly perfect linear fit, or measured Plank constant was clearly inconsistent with the accepted value. Our best measurement lies roughly four and a half standard deviations away from the accepted value (>99.99% confidence interval).
- I believe that systematic error prevailed in this lab, which could have been caused by several factors. As I discuss in my lab notebook, there is a chance that fringe overlaps or charge leaks could have caused us to obtain erroneous measurements for the stopping potential. However, a definitive solution was not discovered, and so the problem is still unresolved.
- If I had more time to explore the photon theory of light and the photoelectric effect, there is one thing that I would like to try -- I would like to build my own photoelectric effect apparatus. This way I would not have to question the accuracy of the black-box, which is inevitable, given that it automatically spits out the voltage readings.
