Viva Voice Questions with Answer
Refractive Index of Material of Glass Slab
For: Science Class 11 | Physics

Q.1: What do you mean by refractive index?
Ans. Refractive index of a medium determines the extent to which one medium is optically denser than the other medium for a particular of a light used.

Q.2: What is absolute refractive index?
Ans. When light passes from vacuum into another medium than the ratio of the since of angle of incidence to the sine of angle of refraction is called absolute refractive index.

Q.3: On what factors refractive index depends?
Ans. It depends:(a) Nature of medium (b) Wave length of incident light.

Q.4: What is the unit and the use of refractive index?
Ans. Being a ratio refractive index has no units and it is used to test the purity of a material because every pure material has a definite refractive index.

Q.5: Why does an object appear near through glass or water?
Ans. It is due to refraction of light.

Q.6: If an object is placed under the glass slab what type of its image is formed?
Ans. Virtual image is formed in the glass slab.

Q.7: What is meant by critical angle?
Ans. When refraction tales place from a denser to rare medium, the angle of incidence for which the corresponding angle of refraction is 90^o is called critical angle.

Q.8: On what factors critical angle depends?
Ans. It depends upon the nature of material and the nature of the medium in which the material is placed. It also changes with the colour of light, greater for red light and smaller for violet light.

Q.9: Define total internal reflection?
Ans. When light strikes the surface of an optically rare medium to an angle of incidence greater than the critical angle, light instead of emerging into the rare medium is reflected back into the denser medium. This phenomenon is called total internal reflection.

Q.10: Under what conditions total internal reflection occur?
Ans. (a) The light must pass from a denser to rare medium.
(b) Angle of incidence in the denser medium must be greater than the critical angle for that
medium.