Explain partial reflection, critical angle and
total internal reflection with the help of a
neat labelled diagram.
Answers
Answer:
When an oblique ray of light travels from optically denser medium to an optically rarer medium, it bends away from the normal at the surface separating the two media.
∙ According to Snells law, the angle of refraction increases with the increase in the angle of incidence. The figure below shows refraction between two media.
∙ As shown in the figure above, the rays AB
2
and AB
3
originating from Point A of the source undergoes partial refraction and partial reflection.
∙ The refracted ray for the incident ray AB
4
travels along the surface separating the two media. So, its angle of refraction is 90
∘
.
∙ When a ray of light travels from the denser medium to the rarer medium, the angle of incidence for which the angle of refraction is 90
∘
is known as the critical angle.
∙ When the angle of incidence exceeds the critical angle, the ray is totally internally reflected. This is the phenomenon of total internal reflection.
