Saturday 2 May 2020

optics - Destructive interference and energy conservation


In case of interference,we know,energy is neither destroyed,nor created; but only redistributed.But in the case of an extremely thin film,due to a reflection and hence a phase difference of pi, the film always appears dark due to destructive interference. So,where does the energy go?




Answer



The logical answer is : into an increase in the motion of the atoms on which individual photons scattered off the thin film, i.e. heat.


This is a fascinating similar phenomenon with monochromatic laser light showing destructive interference. It is instructive to look, as it shows the quantum mechanical dependence of light.


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