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Question 24.AP.4: Diffraction of Sound Waves If a classroom door is open even ...

Diffraction of Sound Waves

If a classroom door is open even a small amount, you can hear sounds coming from the hallway, yet you can’t see what is going on in the hallway. How can this difference be explained?

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The space between the slightly open door and the wall is acting as a single slit for waves. Sound waves have wavelengths larger than the width of the slit, so sound is effectively diffracted by the opening and the central maximum spreads throughout the room. Light wavelengths are much smaller than the slit width, so there is virtually no diffraction for the light. You must have a direct line of sight to detect the light waves.

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