Page 2 - Lesson note refraction through glass slab
P. 2
air1n=sinrsine(1)(1)1n=sinrsineor,n=sinesinr(2)(2)n=sinesinrfrom
equations 1 and 2sini=sine⇒i=esini=sine⇒i=eangle of incidence =
angle of emergence
o It means that incident ray and emergent ray makes equal angles with
parallel normal N1QN2N1QN2 and N3RN4N3RN4 . Hence incident
and emergent rays are parallel.
lateral displacement of light in glass slab
When a ray of light is refracted from two refracting surfaces, the emergent ray
is displaced from the direction of the incident ray. This displacement of the
emergent ray from the path of the incident ray is called lateral shift. i. The
perpendicular distance between the two parallel refracting surfaces.
factors affecting lateral displacement of light in glass slab
(1) The thickness of the glass slab: The lateral displacement increases with the
increase in the thickness of the glass slab. (2) The angle of incidence: It increases
with the increase in the angle of incidence. (3) The refractive index of glass: The
wavelength of light used.
2