If
the wavelength of the incident light is
|
Solution: Click For PDF Version As the ray A is reflected from a medium with greater refractive index than that of the medium on the incident side, it undergoes a phase change of .
The transmitted ray on its reflection from the interface of medium
of refractive index 1.33 and the medium of refractive index 1.26
does not undergo additional phase change, as reflection is from a
medium with lesser refractive index than that of the incident side.
If we assume that the incident ray strikes at
near normal angle, between rays A
and B there is an
additional phase change of
 .
Therefore, the total phase change between waves A
and B is
We are given
that the phase difference between rays A and
B is
Therefore,
As
|
,
the rays A and B, as
shown in the figure, are
out of phase by
.
We have to find the thickness d of the film.
.
