Physics
Physics
Problem
Monochromatic light of wavelength in air strikes a thick coating () on glass () at to the normal. Indicate whether the reflected light at this wavelength will be at a brightness maximum or minimum.Intuitive explanation
This is a thin-film interference problem where you need to track how light reflected from the top and bottom surfaces of the coating interfere with each other. The key is calculating the optical path difference—accounting for both the extra distance light travels through the coating and any phase shift from reflection at higher-refractive-index boundaries. Once you know whether the path difference equals an integer or half-integer multiple of the wavelength in the coating, you can determine constructive or destructive interference.
Intuitive explanation
This is a thin-film interference problem where you need to track how light reflected from the top and bottom surfaces of the coating interfere with each other. The key is calculating the optical path difference—accounting for both the extra distance light travels through the coating and any phase shift from reflection at higher-refractive-index boundaries. Once you know whether the path difference equals an integer or half-integer multiple of the wavelength in the coating, you can determine constructive or destructive interference.