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Name: Charlotte
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I am doing a practical experiment and am required to design a laboratory experiment using a LDR to investigate how the intensity of light emitted by a lamp varies with wavelength. I am wondering what the best way of altering the wavelength of light is in a school laboratory. I was thinking either a prism or coloured filters.. but then how would I MEASURE the wavelength of the light?


Most glass has not one index of refraction but a range for visible light. Usually violet has the greatest index and red has the least. If you wish to use a prism, laws of refraction can tell you at which angle each wavelength will project. You will need a fairly precise set of indices of refraction. I suggest contacting the company that makes the prism. Such a company may even be able to tell you which of their prisms have the greatest range of indices. Quite often the producer of equipment can be a valuable source of information.

Dr. Ken Mellendorf
Physics Instructor
Illinois Central College

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