Questions in Ray Optics and Optical Instruments

Select	Question
	The velocity of light in a medium is half its velocity in air. If ray of light emerges from such a medium into air, the angle of incidence, at which it will be totally internally reflected, is
	A ray of light propagates from glass (refractive index = 3/2) to water (refractive index = 4/3). The value of the critical angle
	Relation between critical angles of water and glass is
	If critical angle for a material to air is $30^o$, the refractive index of the material will be
	The refractive index of water is $1.33$. The direction in which a man under water should look to see the setting sun is
	Optical fibres are related with
	Brilliance of diamond is due to
	A light ray from air is incident (as shown in figure) at one end of a glass fiber (refractive index $\mu = 1.5$) making an incidence angle of $60^o$ on the lateral surface, so that it undergoes a total internal reflection. How much time would it take to traverse the straight fiber of length 1 km
	Light wave enters from medium 1 to medium 2. Its velocity in 2nd medium is double from 1st. For total internal reflection the angle of incidence must be greater than
	Consider telecommunication through optical fibres. Which of the following statements is not true