A cubical vessel has opaque walls. An observer (dark circle in figure below) is located such that she can see only the wall CD but not the bottom. Nearly to what height should water be poured so that she can see an object placed at the bottom at a distance of 10 cm from the corner C ? Refractive index of water is `1.33`.

A cubical vessel with non-transparent walls is so located that the eye of an observer does not see its bottom but sees all of the wall CD. To what height should water be poured into the vessel for the observer to see an object F arranged at a distance of b=10 cm from corner D? The face of the vessel is a=40 cm. Refractive index of water is 4/3.

A cubical vessel with non-transparent walls is so located that the eye of an observer does not see its bottom but sees all of the wall CD. To what height should water be poured into the vessel for the observer to see an object F arranged at a distance of b=10 cm from corner D? The face of the vessel is a=40 cm. Refractive index of water is 4/3.

An object is fixed at the bottom of a vessel and water is filled in the vessel upto a height of 10 cm. A plane mirror is placed at a height of 7 cm from the surface of water in such a way that its reflecting surface faces the water. The distance of the image from the mirror is (Refractive index of water, n = 1.33)

A cylinder has a radius 10 cm. To what height should is be filled with water so that the thrust in its walls is equal to that on its bottom ?

A cylinder has radius 8 cm. Up to what height (in cm) should it be filled with water so that the thrust on its walls is equal to that on its bottom?

A small bulb is placed at the bottom of a tank containing water to a depth of 80cm. What is the area of the bulb can emerge out? Refractive index of water is 1.33. (Consider the bulb to be a point source.)

A small bulb is placed at the bottom of a tank containing water to a depth of 80cm. What is the area of the bulb can emerge out? Refractive index of water is 1.33. (Consider the bulb to be a point source.)