An Air Passenger Sitting In An Aeroplane Flying At A Height Of 2000 Meter From The Earth Takes Photographs Of The Earth. The Focal-length Of His Camera-lens Is 50 Cm. The Size Of The Camera-film Is (18 × 18)cm2. What Maximum Area Can Be Covered By The Camera?      

Glycerine (refractive index 1.4) is poured into a large jar of radius 0.2 m to a depth of 0.1 m. There is a small light source at the centre of the bottom of the jar. Find the area of the surface of glycerine through which the light passes.  

A ray of light travelling in glass (refractive index, _an_g = 3/2) is incident on a horizontal glass-air surface at the critical angle c. If a thin layer of water (refractive index, _an_w = 4/3) is now poured on the glass-air surface, at what angle will the ray of light emerge into air at the water-air surface?

The radius of curvature of the convex surface of a thin plano-convex lens is 20 cm. Refractive index of the medium of the lens is 1.5. Calculate the focal length of the lens.   

The thickness of a plano-convex lens is 4 cm. When it is placed on a horizontal table in such a way that its curved surface be in contact with the table, then the depth of a bottom-point of the lens appears 3 cm. If the lens is inverted so that its plane surface be in contact with the table, then the apparent depth of the centre of the lens-surface is found to be (25/8) cm. Determine the focal-length of the lens.     

The focal length of a convex lens in air is 20 cm. What will be its focal length if it is immersed in a liquid of refractive index 1.35? Refractive index of glass is 1.50.  

A lens made of glass having refractive index 1.5 has a focal length of 50 cm in air. What will be its focal length if it is immersed in a liquid of refractive index 1.2?  

A convex lens of glass (refractive index 1.5) has both surfaces of radius of curvature 20 cm. Find its focal length and nature when it immersed in a liquid of refractive index 1.75. 

The focal length of a lens of glass (n = 1.5) in air is 0.4 m and in a liquid is 1.2m. Determine the refractive index of the liquid.

The radius of curvature of both the surfaces of a double convex lens is R. The refractive index of the material of the lens is 1.5. When a point-source of light is placed on the principal axis of the lens at a distance of 20 cm in-front of the one surface of the lens, then rays emerge from the other surface normally. Determine the radius of curvature R of each surface of the lens.        

The diameter of sun is 1.4 × 10⁹ meter. Determine the diameter of the image of the sun formed by a convex-lens of focal length 1.0 meter. Distance of the sun from the earth is 1.0 × 10¹¹ meter.