Physics307L:People/Dougherty/Notebook/071001

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SJK 00:50, 12 October 2007 (CDT)
00:50, 12 October 2007 (CDT)Overall, the parts of your notebook that I see are well done.  I really like the graphs and the calculation of your final answer with uncertainty from random error.  However, there are many things missing, which are critical for  a good lab notebook.  These include: (1) model # and description of instrumentation; (2) much more description of measurement methods. A good strategy would be to cite the lab manual, and then record all the little details that aren't in the manueal (i.e, "we're using my cell phone for a stop watch, it's a Nokia.") the notes in your notebook should be taken as you go along, and don't have to be written well or anything...the only goal is to record as much information as possible so that later on people (including you) can know what you did.
00:50, 12 October 2007 (CDT)
Overall, the parts of your notebook that I see are well done. I really like the graphs and the calculation of your final answer with uncertainty from random error. However, there are many things missing, which are critical for a good lab notebook. These include: (1) model # and description of instrumentation; (2) much more description of measurement methods. A good strategy would be to cite the lab manual, and then record all the little details that aren't in the manueal (i.e, "we're using my cell phone for a stop watch, it's a Nokia.") the notes in your notebook should be taken as you go along, and don't have to be written well or anything...the only goal is to record as much information as possible so that later on people (including you) can know what you did.


Contents

Experiment 1 Results

UV plot

Untitled.JPG

Blue-Violet plot

Blue_violet.JPG

Green plot

Green.JPG

Yellow 1 plot

Yellow1.JPG

Yellow 2 plot

Yellow_2.JPG

Experiment 2 Results

SJK 00:40, 12 October 2007 (CDT)
00:40, 12 October 2007 (CDT)Good job citing where you obtained this graph!
00:40, 12 October 2007 (CDT)
Good job citing where you obtained this graph!

http://dev.physicslab.org/Document.aspx?doctype=3&filename=AtomicNuclear_PhotoelectricEffect.xml

image:KEvsFreq.jpg Photoelectric Effect/Stopping Potential Relations

Graphs

SJK 00:42, 12 October 2007 (CDT)
00:42, 12 October 2007 (CDT)The data in these sections look really good!  Although they are not labeled particularly well so that someone would know how the data were obtained.  For example, what is 1st order / 2nd order? Even you in a few months would probably be confused!
00:42, 12 October 2007 (CDT)
The data in these sections look really good! Although they are not labeled particularly well so that someone would know how the data were obtained. For example, what is 1st order / 2nd order? Even you in a few months would probably be confused!

1st_1st.JPG

   h = 6.92*10^-34 J    W0 = 2.373*10^-19 J

1st_2nd.JPG

   h = 6.99*10^-34 J    W0 = 2.416*10^-19 J

2nd_1st.JPG

   h = 7.32*10^-34      W0 = 2.587*10^-19 J

2nd_2nd.JPG

   h = 7.29*10^-34 J    W0 = 2.569*10^-19 J

Mean Value

    h = 7.13*10^-34     W0 = 2.48625*10^-19 J

Standard Deviation


s = \sqrt{\frac{1}{N-1} \sum_{i=1}^N (x_i - \overline{x})^2}
    s = 2.04450484*10^-35

Standard Error of the Mean

SJK 00:45, 12 October 2007 (CDT)
00:45, 12 October 2007 (CDT)As far as I see, you calculated the standard error of the mean correctly...good work!
00:45, 12 October 2007 (CDT)
As far as I see, you calculated the standard error of the mean correctly...good work!

s = \sqrt{\frac{1}{N-1} \sum_{i=1}^N (x_i - \overline{x})^2}
SE = \frac{s}{\sqrt{N}}
    SE = 1.02225242*10^-35

"Planck's Constant"

    7.13*10^-34 +/- 1.02225242*10^-35

Error

SJK 00:45, 12 October 2007 (CDT)
00:45, 12 October 2007 (CDT)Great comparison with the accepted value...you would want to include this very relevant info in your summary!
00:45, 12 October 2007 (CDT)
Great comparison with the accepted value...you would want to include this very relevant info in your summary!

%error= \frac{|Actual-Experimental|}{|Actual|}x100

   %error = 7.54%

reasons for errors

SJK 00:32, 12 October 2007 (CDT)
00:32, 12 October 2007 (CDT)I would say possible errors, and then add some explanation as to how this may affect the data, and what you think is most likely.  It appears your h is too high, which means your slope is too high...how would bad filters or extraneous light produce this effect?
00:32, 12 October 2007 (CDT)
I would say possible errors, and then add some explanation as to how this may affect the data, and what you think is most likely. It appears your h is too high, which means your slope is too high...how would bad filters or extraneous light produce this effect?

light filtering in from other sources

bad filters on the apparatus

bad volt meter

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