Q37 of 79 Page 380

A parallel beam of white light is incident normally on a water film 1.0 × 10-4 cm thick. Find the wavelength in the visible range 1400 nm-700 nm) which are strongly transmitted by the film. Refractive index of water = 133.

Given, refractive index,

And thickness of the film be the


Here, the light is strongly transmitted.


therefore,




now, for n=4



now, for n=5



now, for n=6



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