A researcher measures the thickness of a layer of benzene (n = 1.50) floating on water by shining monochromatic light onto the film and varying the wavelength of the light. she finds that light of wavelength 600 nm is reflected most strongly from the film. part a what does she calculate for the minimum thickness of the film? express your answer with the appropriate units.

Question

Physics

Olive Barry

5 May, 12:27

A researcher measures the thickness of a layer of benzene (n = 1.50) floating on water by shining monochromatic light onto the film and varying the wavelength of the light. she finds that light of wavelength 600 nm is reflected most strongly from the film. part a what does she calculate for the minimum thickness of the film? express your answer with the appropriate units.

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Emely Franco · Answer 1

This problem relates to interference of light in thin films.

The condition of bright fringe in thin films which is sandwitched by two layers of medium having lesser refractive index is as follows.

2nt = (2n+1) λ / 2, n is refractive index of thin layer, t is its thickness, λ is wavelength of light.

2 x 1.5 t = λ / 2, if n = 0 for minimum thickness.

2 x 1.5 t = 600 / 2 nm

t = 100 nm.