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Physics Experiment Involving Light - Ideas Please

  1. Jan 7, 2014 #1
    Physics Experiment Involving Light -- Ideas Please

    Hello,

    I have to do an investigation which should be completed in 20 hours over 4 weeks.
    I am interested in investigating light such as Wave-Particle Duality but
    it is probably impossible to do anything on it in a school lab.

    Therefore I thought about an experiment that has to
    do with Diffraction of light but I didn't decide
    what should I specifically try to find out in it.

    Can anyone suggest me any interesting and ideally original investigation that
    has to do with photons and light or even some other investigation that
    can be completed in a school lab.

    Thank you.

    NeoXx
     
  2. jcsd
  3. Jan 7, 2014 #2

    ZapperZ

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    What level of school is this? Graduate level, undergraduate level, high school, middle school, kindergarten?

    What type of facilities and equipment are available to you? What do you have?

    Zz.
     
  4. Jan 7, 2014 #3

    sophiecentaur

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    Do you have any ideas at this stage?
    Look into history to see what evidence came to light that suggested light does not always behave as a wave. You may well have a suitable piece of equipment that would show it, in your Physics prep room.
     
  5. Jan 7, 2014 #4
    It is a high school and there are variety of equipment available,
    probably much more than in average school.

    I will certainly look at the evidence.

    Thanks for replying.

    NeoXx
     
  6. Jan 7, 2014 #5
    The thing Sophie reffered to in hopes you would guess it was the photoelectric effect , and it would actually be quite easy to replicate and it's a fundamental thing in physics.
    Consider it a good proposal.

    http://en.wikipedia.org/wiki/Photoelectric_effect
     
  7. Jan 7, 2014 #6
    Photoelectric effect experiment seems interesting.
    However it seems to me that it is a very short experiment,
    correct me if I am wrong.
     
  8. Jan 7, 2014 #7
    Am what do you mean by " short experiment" ?

    Would you rather want an experiment which goes on for days until it produces the outcome?

    many many processes and interactions in physics happen very quickly , have you ever seen explosion or rapid expansion happening slow for example? t wouldn't be rapid expansion then anymore.
    Particle interactions happen fast but in a photoelectric effect the most important part is that they happen at all , also the energy of the outcoming electrons will depend on the incoming light or em radiation frequency , but the intesnity of how much electrons you will get will be proportional to the intensity of light you will shine upon the plate.

    You can leave the experiment going on for days , it would still do what it did in the first seconds , so in that sense there is nothing short of it. :)
     
  9. Jan 7, 2014 #8

    sophiecentaur

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    Launching a space rocket only takes a few minutes - but there are years of preparation and report writing involved. Do not be fooled into thinking that getting a photoelectric effect experiment to work will only take a short time. You will need to do a fair bit of reading for a start and getting the appropriate equipment to work. What would you expect to use? (A sketch might help.)
     
  10. Jan 8, 2014 #9
    Giving it another thought I was wrong in saying that the experiment will be short especially since I will have to read a lot about the topic and write the report as well.
    I concluded I will investigate the photo electric effect and do the experiment.
    Thanks for the help everyone! :)
     
  11. Jan 8, 2014 #10
    if you face any problem or quesions along the way be sure to pay a visit here:)
     
  12. Jan 8, 2014 #11

    sophiecentaur

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    You can fairly easily demonstrate the 'existence' of the photoelectric effect, using zinc, an electroscope and a UV lamp. The nicer experiment uses a range of frequencies of light and potassium metal in an evacuated container. Much harder to set up (expensive specialist equipment) but will yield the Einstein (Nobel prizewinning) result which shows the photon energy vs the KE of the photoelectrons.
    But the task you have been set will be appropriate to your resources and ability so you should be fine.
     
  13. Jan 14, 2014 #12
    After speaking to my physics teacher I decided that
    I could investigate the diffraction and interference happening
    on CD/DVD and Blu-ray discs.

    Investigating photoelectric effect by doing a nicer experiment would
    require equipment our school lab doesn't have (potassium metal etc.).

    What do you think, would the experiment with optical discs be interesting
    and what do you think should I specifically investigate in the experiment?


    Regards.
     
  14. Jan 14, 2014 #13

    sophiecentaur

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    Diffraction is a good topic to study and will give reliable results if you are careful. He's OK with the fact that the particle nature of light doesn't come into it?
     
  15. Jan 14, 2014 #14
    What do you mean?
     
  16. Jan 14, 2014 #15

    ZapperZ

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    In your first post, your goal was to do something to "demonstrate" the wave-particle duality. A typical diffraction experiment doesn't quite show such a thing clearly.

    Zz.
     
  17. Jan 14, 2014 #16

    sophiecentaur

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    Perhaps the 'straight line' motion (rectilinear propagation) would be enough to justify the particle model.
     
  18. Jan 14, 2014 #17
    Yes it was my first goal.
    But my goal in this experiment is not to demonstrate Wave-Particle Duality anymore
    but to investigate diffraction and interference of light in optical discs.
    My goal here will be to show the differences between those optical discs and maybe
    conclude how they could be improved (discs with more space for example).

    To be honest I am still not certain about the main goal but
    this experiment interests me.
     
  19. Jan 14, 2014 #18

    sophiecentaur

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    Ah well - as long as your tutor is happy with the altered terms it will be fine. What would you hope to achieve in this project? It's normal to find a bit of theory you can understand and then verify it by experiment. For instance, you could find the spacing between the lines of bits and use that to deduce how much information it would be able to pack onto the surface. Compare CD and DVD, for instance and then check with the data about them.
     
  20. Jan 14, 2014 #19
    I would love to investigate the behaviour of light such as in double slit experiment or glass reflection and prove the photoelectric effect or wave particle duality. However the lab does not have the required equipment for those experiments. There is the equipment to fairly demonstrate the photoelectric effect but the investigation wouldn't be as accurate and as in depth as I would want it to be.
    Therefore I had to choose another experiment concerning light and the one with optical discs appealed to me. :)
     
  21. Jan 14, 2014 #20
    FYI: You can build a simple spectrograph/spectrometer with a CD (or a piece of a CD). You also need some other things, but they are quite easy to construct. Google for "DIY spectrometer" or "how to make a spectrometer" if you are interested.

    EDIT: I googled myself and I found some more advanced DIY electronic versions. I just want to underline I meant a simple one, that is: a slit, a CD piece and a box.
     
    Last edited: Jan 14, 2014
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