A pile 4m high driven into bottom of a lake is 1 m above the water. Determine the length of the shadow of the pile on the bottom of the lake if the sunrays make an angle of 45o with the water surface. The refractive index of water is 4/3.


Correct option is

2.88 mt






Length of shadow = DF = DE + EF

                                           = 2.88 mt



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 1cm floating on the surface.  The center of the disc lies vertically above the surface 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 seen from above.



One end of a long glass rod (μ = 1.5)is formed into a convex surface of radius 6.0 cm. An object is positioned in air along the axis of the rod. Find the image positions corresponding to object distances of

(a)  20.0 cm                    (b )10.0 cm

(c)  3.0 cm    From the end of the rod



The left end of a long glass rod of index 1.6350 is ground and polished to a convex spherical surface of radius 2.50 cm. A small object is located in the air and on the axis 9.0 cm from the vertex. Find the lateral magnification.



Two thin similar convex glass pieces are joined together front to front, with its rear portion silvered such that a sharp image is formed 0.2 m for an object at infinity. When the air between the glass pieces is replaced by water (μ = 4/3), find the position of image.


When a lens is inserted between an object and a screen which are a fixed distance apart the size of the image is either 6 cm or 2/3 cm. find size of the object



Light is incident normally on the short face of a 30o – 60o – 90oprism. A liquid is poured on the hypotenuse of the prism. If the refractive index of the prism is √(3,) find the maximum refractive index of the liquid so that light is totally reflected




A ray of light passing through a prism having refractive index √(2) suffers minimum deviation. It is found that the angle of incidence is double the angle of refraction within the prism. what is the angle of prism?


 In a glass sphere, there is a small bubble 2 ×10-2 m from its centre. If the bubble is viewed along a diameter of the sphere, from the side on which it lies, how far from the surface will it appear? The radius of glass sphere is 5 ×10-2 m and refractive index of glass is 1.5



Considering normal incidence of ray, the equivalent refractive index of combination of two slabs shown in figure is