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Homework Help: Light Interference patterns

  1. Apr 24, 2007 #1
    1. The problem statement, all variables and given/known data
    What characteristic of light is needed to produce interference patterns? ( like the grainly pattern of light demonstrated in lab)

    3. The attempt at a solution
    ok,, so i missed lab and did a makeup so I never saw what is being described. I am guessing that the grainy pattern of light means that it was destructive interference, but I am not sure. my guess would be that the only requirment is for the light to be Coherent Light, but I really dont know, can anyone point me in the right direction? thanks in advance.
  2. jcsd
  3. Apr 24, 2007 #2
    I found this in my book / on the web as well:

    In 1801, Thomas Young successfully showed that light does produce a two-point source interference pattern. In order to produce such a pattern, monochromatic light must be used. Monochromatic light is light of a single color; by use of such light, the two sources will vibrate with the same frequency.

    is this what I am looking for? would this mean the light needs to be Monochromatic?
  4. Apr 30, 2007 #3
    Yes. You need monochromatic light (of constant frequency) to create what they call a 'fringe pattern' on a screen, after the light passes through two slits. Ordinary light (like that which comes from conventional light bulbs) would not work.

    Thomas Young first did this in 1801, as you say, and first demonstrated interference of light. Google 'Thomas young double slit experiment' and you'll find a lot of things.
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