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Strange Planck's Constant Data

  1. Aug 6, 2009 #1
    I was doing a practical to analyse for my school assessment with regard to Planck's constant. I was using a Planck's constant kit to get some results but the results I was getting was inconsistent with my research as seen below. Isn't the voltage meant to increase as the wavelength is shorter? My results seem really muddled up and I did it again and it still came out with the same results. Perhaps there is something wrong with the machine or is this just the way it is meant to be?


    Aperture Diameter (mm)
    7
    10
    14
    20
    N/A (fully exposed)

    Results aligned with aperture size list (I couldn't put the table on here)

    Blue 428nm Voltage (V)
    0.37
    0.68
    1.06
    1.31
    1.35

    Green 460nm
    Voltage (V)
    0.19
    0.34
    0.71
    0.98
    1.01

    Yellow 492nm
    Voltage (V)
    0.77
    1.11
    1.36
    1.50
    1.52

    Orange 530nm
    Voltage (V)
    0.28
    0.55
    0.91
    1.13
    1.16

    Red 590nm
    Voltage (V)
    0.07
    0.15
    0.27
    0.44
    0.48
     
  2. jcsd
  3. Aug 6, 2009 #2
    Your results show that the voltage does increase as the wavelength gets shorter. Red waves were the longest and blue waves the shortest.
     
  4. Aug 7, 2009 #3
    Yes but why is yellow greater than blue? It should be just a bit greater than red.
     
  5. Aug 7, 2009 #4
    Oh yes, I see what you mean.First time I just scanned the numbers but your post above forced me to look more carefully.Forget yellow for the moment and the trend for the other wavelengths seems to be correct.Now why the anomolous results for yellow?Did you use filters ?If so these transmit a range of wavelengths and perhaps the yellow filter was of lower quality compared to the others.Perhaps you could look up the characteristics of the filters you used.Of course I'm not familiar with the equipment you used or what you did but your overall results look pretty good to me and I would go ahead and process them anyway.I imagine you would get some pretty good graphical plots with yellow standing out as an anomoly.Don't worry about anomolies,unless you get the opportunity to go back and recheck them experimentally there is nothing you can do about them, but you can write about them and come up with some suggestions as to why they cropped up.
     
  6. Aug 7, 2009 #5
    Yes I did use filters. Those were the five that were available. I did it again the next day and the results were similar to those.

    I can't think of any reasoning for the systematic error as that was my first time ever using it. I also can't find any particular sites that may account for this anomaly online either.
     
  7. Aug 7, 2009 #6
    My feeling is that the yellow filter was transmitting some shorter wavelength components but I just don't know.Hopefully others will come in here with some suggestions.It seems to me that you have done just about everything you can, so if I was you I wouldn't bother about it and go ahead and process your results.
     
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