# Fat light

1. Apr 21, 2005

### T@P

i just learned this in physics, and i dont quite understand something:

according to Huygens, (i think) light is a ciruclar wave, and at everypoint on the wave there are wavelets. because there are so many ways for the wavelets to form, light takes every possible path from point a to point b. that parts sort of makes sense. then, all the really weird paths get cancelled, out and you are left with essentially a cone of light.

the above (if i got it right) sort of makes sense. but what doesnt is that this is supposed to explain why when you make a pinhole thats too small you get blurryness. shouldnt you just get the image to be not as bright? i dont quite see where the blurry part comes in.

2. Apr 21, 2005

### shyboy

If you have a small pinhole, you can get a diffraction from opposite edges.
So, if you ahe a single source, you will get a bright central (main) peak and a lot of small peaks resulting from the diffraction. http://upload.wikimedia.org/wikipedia/en/e/e1/Diffraction1.png [Broken]

The smaller the hole the stronger will be peaks. For a circular hole , I guess, you have additional rings. So your total image, produced by multiple sources will be blurred.

Last edited by a moderator: May 2, 2017
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