Ray Optics and ...

An observer looks at a tree of height 15 metre with a telescope of magnifying power 10. To him, the tree appears

The magnifying power of the telescope can be increased by

The largest telescope in the world has a reflector with an aperture of 200 inches in order to achieve

How will the image formed by a convex lens be affected if the central portion of the lens is wrapped in a black paper?

A bird flies down vertically towards a water surface. To a fish inside the water, vertically below the bird, the bird will appear to

The layered lens is made of two kinds of glass. A point source of light is placed on its principal axis. If the reflections from the boundaries between layers are ignored, the lens will form

Spherical aberration in a thin lens can be reduced by

A point object is placed at the centre of a glass sphere of radius 6 cm and refractive index 1.5. The distance of virtual image from the surface of sphere is