Geometrical OpticsEasy
Question
Light enters at an angle of incidence in a transparent rod of refractive index n. For what value of the refractive index of the material of the rod the light once entered into it will not leave it through its lateral face whatsoever be the value of angle of incidence :-
Options
A. n > √2
B.n = 1
C.n = 1.1
D.n = 1.3
Solution
From the following figure
r + 1 = 90o ⇒ i = 90o - r
For ray not to emerge from curved surface i > C
⇒ sini > sinC ⇒ sin(90o -r) > sinC ⇒ cosr > sinC
⇒
⇒ 1 -
⇒ 1 > 
(1 + sin2α)⇒ n2 > 1 + sin2α ⇒ n > √2 {sini → 1}
⇒ Least value = √2
Create a free account to view solution
View Solution FreeMore Geometrical Optics Questions
The focal length of a convex mirror is 20 cm its radius of curvature will be...A telescope has an objective lens of focal length 150 cm and an eyepiece of focal length 5 cm. If a 50 m talltower at a ...Monochromatic light is refracted from air into the glass of refractive index m. The ratio of the wavelength of incident ...A ray of light normally on the first refracting face of the prism of refracting angle A. The ray of light comes out at g...There are two plane mirror with reflecting surfaces facing each other. Both the mirror are moving with speed v away from...