Physics
The critical angle for glass-air is 45° for the light of yellow colour. State whether it will be less than, equal to, or more than 45° for
(i) red light,
(ii) blue light ?
Answer
As the wavelength of light decreases (or increases) refractive index becomes more (or less) and critical angle becomes less (or more).
(i) As the wavelength for red light is more than that for yellow colour, the refractive index becomes less and the critical angle will be more than 45°.
(ii) As the wavelength for blue light is less than that for yellow colour, the refractive index becomes more and the critical angle will be less than 45°.
Related Questions
State the approximate value of the critical angle for
(a) glass-air surface
(b) water-air surface.
A light ray is incident from a denser medium on the boundary separating it from a rarer medium at an angle of incidence equal to the critical angle. What is the angle of refraction for the ray?
Which colour of light has higher critical angle ? Red light or green light.
Fill in the blanks to complete the following sentences —
(a) Total internal reflection occurs only when a ray of light passes from a ………. medium to a ………. medium.
(b) Critical angle is the angle of ………. in denser medium for which the angle of ………. in rarer medium is ……….