Ray Optics Test...

A point source of light B, placed at a distance L in front of the centre of a mirror of width d, hangs vertically on a wall. A man walks in front of the mirror along a line parallels to the mirror at a distance 2 L from it as shown in Fig. The greatest distance over which he can see the image of the light source in the mirror is

Magnifying power of telescope can be increased by

A doctor advises a patient to use spectacles with a convex lens of focal length 40 cm in contact with a concave lens of focal length 25 cm. What is the power of the combination?

A disc is placed on a surface of pond which has refractive index 5/3. A source of light is placed 4 m below the surface of liquid. The minimum radius of disc needed so that light is not coming out is

Wave lengths of light used in an optical instrument are λ = 4000 Ǻ and λ = 5000 Ǻ. The ratio of their respective resolving power is

The objective of an astronomical telescope has a large aperture to

The Cauchy’s dispersion formula is

An observer can see through a pin hole, the top end of a thin rod of height h placed as shown in Fig. The beaker height is 3h and its radius is h. When the beaker is filled with a liquid upto a height 2h, he can see the lower end of the rod. Then the refractive index of the liquid is

The image formed by an objective of a compound microscope is

A convex lens is dipped in a liquid whose refractive index is equal to the refractive index of the lens. Then its focal length will