If an EM wave generated by example from a laser has a wavelength l greater but close to the width of a slit d (say 1.2-2 times bigger l=(1.1-2)d will some radiation (photons) pass through the slit? If they pass will they change their l? As I think this is just diffraction and l does not change. If they can not pass why? If one applies Hyugence principle there should be a wave behind tne slit?
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When you're dealing with wave phenomena, forget photons and use wave models.
Babinet's Principle is more illuminating than Huygens' here. Objects of size comparable to the wavelength are very effective scatterers of light. Thus, apertures of similar size are effective at transmission. A narrow slit in a conductive sheet half a wavelength long can serve as an effective resonant antenna.
Even much smaller apertures can transmit some light. Consider the blue sky, where molecules are responsible for the scattering. However, the reflection is strongly favored over transmission for apertures much smaller that 1/2 wavelength.
John Doty
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The laser EM wave is made up of many quanta (also called photons), each quanta was emitted by a single excited atom .... eventually each quanta will be absorbed by another atom like at atom on the screen.
Each quanta is acting on its own,
each quanta's path is guided by the EM field which is very dynamic,
each quanta has energy and wave properties,
each quanta can NOT be broken into separate parts or waves,
each quanta has a defined energy/frequency/wavelength created by the original band gap of the excited atom,
each quanta will only be absorbed by an atom/molecule with the correct bandage energy,
each quanta is capable of superposition in the EM field but we can never observe this directly.
Huygens principle is very old and it approximates light behaviour when there are many photons .... however Huygens principle makes no sense when we talk about single quanta as they do NOT separate.
PhysicsDave
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