In Fig. 4.63, PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS.
(a) State the special name given to the angle of incidence ∠PQN of the ray PQ.
(b) What is the angle of refraction for the refracted ray QS?
(c) Name the phenomenon that occurs if the angle of incidence ∠PQN is increased.
(d) The ray PR suffers partial reflection and refraction on the water-air surface. Give reason.
(e) Draw in the diagram the refracted ray for the incident ray PR and hence show the position of image of the object P by the letter P' when seen vertically from above.
In Fig. 4.63, PQ and PR are the two light rays emerging from an object P. The ray PQ is refracted as QS.
(a) State the special name given to the angle of incidence ∠PQN of the ray PQ.
(b) What is the angle of refraction for the refracted ray QS?
(c) Name the phenomenon that occurs if the angle of incidence ∠PQN is increased.
(d) The ray PR suffers partial reflection and refraction on the water-air surface. Give reason.
(e) Draw in the diagram the refracted ray for the incident ray PR and hence show the position of image of the object P by the letter P' when seen vertically from above.
(a) Critical angle
The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90∘ is called the critical angle.
(b) 90∘
(c) Total internal reflection.
When the angle of incidence is greater than the critical angle, the phenomenon of total internal reflection occurs due to which the ray of light is not refracted but is reflected back in the same medium.
(d) For the ray PR, the angle of incidence is less than the critical angle, i.e., ∠PQS. Hence at the interface of two media, as per the laws of reflection, ray PR suffers partial reflection and refraction.
(e)
(a) Critical angle
The angle of incidence in the denser medium for which the angle of refraction in the rarer medium is 90∘ is called the critical angle.
(b) 90∘
(c) Total internal reflection.
When the angle of incidence is greater than the critical angle, the phenomenon of total internal reflection occurs due to which the ray of light is not refracted but is reflected back in the same medium.
(d) For the ray PR, the angle of incidence is less than the critical angle, i.e., ∠PQS. Hence at the interface of two media, as per the laws of reflection, ray PR suffers partial reflection and refraction.
(e)
