A fish in water (refractive index n ) looks at a bird vertically above in the air. If y is the height of the bird and x is the depth of the fish from the surface, then the distance of the bird as estimated by the fish is

A man stnading in a swimming pool looks at a stone lying at the bottom. The depth of the swimming pool is h. At what distance from the surface of water is the image of the stone formed? (Line of vision is normal, Refractive index of water is n)

A crane flying 6 m above a still clear water lake sees a fish under water. For the crane the fish appears 6 cm below the water surface. How much deep should the crane immerse its beak to pick that fish? For the fish, how much above the water surface does the crane appear? R.I. of water = frac(4)(3)

A tank is filled with water up to a height H . Water is allowed to come out of a hole P in one of the walls at a depth D below the surface of water. Express the horizontal distance x in terms of H and D .

A tank is filled with water to height of 12.5 cm. The apparent depth of a needl lying at the bottom of the tank is measured by a microscope to be 9.4 cm. What is the refractive index of water? If water is replaced by a liquid of refractive index 1.63 upto the same height, by what distance would the microscope have to be moved to focus on the needle again?

A ray of light travels from air to water to glass and again from glass to air. Refractive index of water with respect to air is ‘x’ glass with respect to water is ‘y’ and air with respect to glass is ‘z which one of the following is correct?

A hollow shpere has a smalll hole. When the sphere is taken to a depth of 0.5 m inside water the air bubble start coming out from the hole. If the surface tension of water is 70xx10^-3 N//m , the radius of the hole is

A glass slab of thickness 2.5 cm having refractive index 5//3 is kept on an ink spot. A transparent beaker of very thin bottom containing water of R.1. 4//3 upto 8 cm is kept on the glass block. Calculate the apparent depth of the ink spot, when seen from outside air.

Read the paragraph and answer the questions given below : Locomotion is considered as an important characteristics of the animals. However, animals belonging to Porifera are said to be sedentary. Every other phylum has typical locomotory organs. E.g. Nereis crawls with the help of parapodia, whereas earthworm buries in soil by setae. Spiders have four pairs of walking legs, crab has five while all insects have three pairs of walking legs. The walking legs are also called appendages. Starfish moves with the help of tube feet. Snails and bivalves use muscular foot for locomotion. Birds flying with their spread out wings and fish swimming with their fins, both have spindle-shaped body tapering at both the ends. While flying or swimming such body offers least resistance during locomotion. Mammals have two pairs of limbs while animals like snakes are limbless. Other animals belonging to the class of snakes also have very weak limbs.which make them creep on the ground. Answer the question: In which class of animals the forelimbs are modified?