Ray Optics and ...

The magnifying power of the telescope can be increased by

A lamp and a screen are set up 100 cm apart and a convex lens is placed between them. The two positions of the lens forming real images on the screen are 40 cm apart. What is the focal length of the lens ?

The magnifying power of telescope is high if

Refraction is

Accommodation of the human eye is

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

A convex lens forms a real image of an object on a screen; the magnification of the image being 3/2. The object and the screen are kept fixed and the lens is moved through a distance of 16 cm when a sharp image is again formed on the screen; the magnification now being 2/3. What is the focal length of the lens?

A plano-convex lens, when silvered on the plane side, behaves like a concave mirror of focal length 30 cm. When it is silvered on the convex side, it behaves like a concave mirror of focal length 10 cm. The refractive index of the material of the lens is

For a rectangular slab, refraction takes place at

Farsighted or hypermetropic eye can be corrected by