Light wavelength measurement

  • Thread starter alikim
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In school we somehow measured the minimum and maximum wavelength our eyes could see

Unfortunately, all I remember is that we were looking through a slit between jaws of some sort of calipers and used a ruler to do measurements

Can anyone please give me an insight of how to set up such experiment?

Thanks!
 

Answers and Replies

  • #2
HallsofIvy
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The sort of experiment I remember doing in secondary school is this: take a pair of microscope slides and wrap a rubber band about the two at one end. Take a source of mono-chromatic light (for "minimum and maximum wavelength our eyes could see" use sources of blue and red light) and shine on the slides. Because you have bound one end of the slides together more firmly than the other, there will be a slight airgap. The light will be reflected from both sides of the air gap so that the two waves will have a slight phase difference, the difference depending on the size of the gap which increases toward the open end. That will result in "cancellation" at some distance, "reinforcement" at others so you can see bands of light on the top slide. The width of those bands is easily measured and the wave length of the light calculated from that. I don't remember the details of the calculation.
 
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Drakkith
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The sort of experiment I remember doing in secondary school is this: take a pair of microscope slides and wrap a rubber band about the two at one end. Take a source of mono-chromatic light (for "minimum and maximum wavelength our eyes could see" use sources of blue and red light) and shine on the slides. Because you have bound one end of the slides together more firmly than the other, there will be a slight airgap. The light will be reflected from both sides of the air gap so that the two waves will have a slight phase difference, the difference depending on the size of the gap which increases toward the open end. That will result in "cancellation" at some distance, "reinforcement" at others so you can see bands of light on the top slide. The width of those bands is easily measured and the wave length of the light calculated from that. I don't remember the details of the calculation.
Interesting. If you happen to remember what this experiment is called or have a link to it please give it to me. I'd love to look into it.
 

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