Pick out the longest wavelength from the following types of radiations.

A telescope has an objective lens of 10cm diameter and is situated at a distance of one kilometre from two objects. Find out the minimum distance between these two objects, which can be resolved by the telescope, when the mean wavelength of light is 5000 Å.

Which of the following phenomenon is not common to sound and light waves?

Colours of thin soap bubbles are due to :s

Which of the following phenomenon is not explained by Huygen's construction of wavefront?

Rainbows are formed by

One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face, forms an image 12 cm behind the silvered face. The refractive index of the glass is :

A lens is placed between a source of light and a wall. It forms images of area A₁ and A₂ on the wall, for its two different positions the area of the source of light is :

If two mirrors are kept inclined at 60° to each other and a body is placed at the middle, then total number of images formed is :

A convex lens of focal length 80 cm and a concave lens of focal length 50 cm are combined together. What will be their resulting power?