A point source of light `S` is placed at the bottom of a vessel containing a liquid of refractive index `5//3`. A person is viewing the source from above the surface. There is an opaque disc of radius `1 cm` floating on the surface. The centre of disc lies vertically above the source `O`. The liquid from the vessel is gradually drained out through a tap. What is the maximum height of the liquid for which the source cannot be seen at all.

A point source of light S is placed at the bottom of a vessel containg a liquid of refractive index 5//3. A person is viewing the source from above the surface. There is an opaque disc of radius 1 cm floating on the surface. The centre of the disc lies vertically above the source S. The liquid from the vessel is gradually drained out through a tap. What is the maximum height of the liquid for which the source cannot at all be seen from above?

A point source of light is placed at a depth of h below the surface of water of refractive index mu . A floating opaque disc is placed on the surface of water so that light from the source is not visible from the surface. The minimum diameter of the disc is

A point source of light is placed at a depth of h below the surface of water of refractive index mu . A floating opaque disc is placed on the surface of water so that light from the source is not visible from the surface. The minimum diameter of the disc is

A point source of light is placed at the bottom of a vessel which is filled with water of refractive index mu to a height h. If a floating opaque disc has to be placed exactly above it so that the source is invisible from above, the radius of the disc should be-

A small illuminated bulb is at the bottom of a tank, containing a liquid of refractive index mu upto a height H. Find the expression for the diameter of an opaque disc, floating symmetrically on the liquid surface in order to cut- off the light from the bulb.

A small illuminated bulb is at the bottom of a tank, containing a liquid of refractive index mu upto a height H. Find the expression for the diameter of an opaque disc, floating symmetrically on the liquid surface in order to cut- off the light from the bulb.