Diffraction: Feynman's Physics Explained
When light passes through a small opening it spreads out — that is diffraction. It looks like a separate effect from interference but is really the same thing: treat every point in the opening as a new tiny source of waves, add up all their contributions, and you get the spreading pattern of light reaching into the shadow. This is what ultimately limits the resolving power of telescopes and microscopes.
The big idea
Waves bend around edges and through gaps — that limits every instrument.
Think about it
Why does sound easily travel around a corner while light casts a fairly sharp shadow? (Hint: compare their wavelengths.)
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