Radio waves from an antenna travel with the velocity of:

A point object is placed at the centre of a glass sphere of radius 6 cm 3 and RI = \(\frac{3}{2}\). The distance of virtual image from the surface of the sphere is :

The RI. of the material of a prism is √2 and its refracting angle is 30°. One of the refracting surface of the prism is made a mirror. A beam of monochromatic light entering the prism from the other face retraces its path, after reflection from mirror surface. The angle of incidence on prism is:

A telescope has an objective lens of 10 cm diameter and is situated at a distance of 1 km from two objects. The minimum distance between these two objects, which can be resolved by the telescope, when seen in the light of mean λ = 5000 A is of the order of:

When a beam of light is used to determine the position of an object, the maximum accuracy is achieved if the light is :

A convex lens is dipped in a liquid, whose R.I. is equal to that of R.I. of material of the lens. Then its focal length will:

The velocity of light in vacuum is 3 × 10¹⁰ cms^-1. The velocity of light in a medium (µ = 1.5) is:

Which of the following is not essential for the formation of a pure spectrum?

A certain far-sighted person cannot see objects closer to the eye than 100 cm. The power of the lens which will enable him to read at a distance of 25 cm will be?

Which produces additional luminiscence in a fluorescent tube?