The refracting angle of a prism is A and the refractive index of the prism is cot (A/2). The angle of minimum deviation is:  


Correct option is





A thin equiconvex lens has focal length 10 cm and refractive index 1.5. One of its faces is now silvered and for an object placed at a distance u in front of the lens, the image coincides with the object. The value of u is:


The plane face of a plano-convex lens of focal length 20 cm is silvered. What type of mirror will it become and of what focal length 


A convex lens of focal length 20 cm is cut into two equal parts so as to obtain two plano-convex lenses as shown in figure. The two parts are then put in contact as shown in figure. What is the focal length of the combination?



As shown in figure, a convergent lens is placed inside a cell filled with liquid. The lens has focal length +20cm when in air, and its material has refractive index 1.50. If the liquid has refractive index 1.60, the focal length of the system is: 



A plano-convex lens of f = 20 cm is silvered at plane surface. Now, f will be (μ = 1.5): 


The plane face of a plano-convex lens is silvered. If μ be the refractive index and R, the radius of curvature of curved surface, then the system will behave like a concave mirror of radius of curvature:


A convex lens of focal length f is placed somewhere in between an object and a screen. The distance between the object and the screen is x. If the numerical value of the magnification produced by the lens is m, the focal length of the lens is:  


A ray of light suffers minimum deviation when incident on a 60o prism of refractive index  The angle of incidence is:


A ray is incident at an angle of incidence i on one face of a prism of small angle A and emerges normally from the opposite surface.  If the refractive index of the material of the prism is μ, the angle of incidence i is nearly equal to: 


A ray of light passes through an equilateral prism of glass in such a manner that the angle of incidence is equal to the angle of emergence and each of these angles is equal to (3/4) of the angle of prism. The angle of deviation is: