Question

A thin film of soap solution (n=1.4) lies on top of a glass plate (n=1.5).When visible light is incident almost normal to the plate,two adjacent reflection maxima are observed at two wavelength 400nm and 630nm.The minimum thickness of soap solution is??

Answer 1

@vincent-lyon.fr

Answer 2

The incident light ray reflects and refracts at point \(a\).
Let \r_1\) be the reflected ray at point \(a\)

Answer 3

What can you say about the phase difference between the incident ray \(i\) and the reflected ray \(r_1\) ?

Answer 4

Lamda/2 is the path diff ..

Answer 5

I'm asking about the phase difference between \(i\) and \(r_1\),
not the path length