Question

In figure, a ray of light $PQ$ is incident normally on the hypotenuse of an isosceles right angle prism $ABC$. Name the device in which this action is used.

• A. Binoculars
• B. Monocular
• C. Periscope
• D. All of the above

Answer 1

The correct option is A Binoculars

A binocular consists of two such prisms that allow a ${180}^o$ angle of deviation. The light rays fall on the first prism and undergoes ${180}^o$ angle of deviation which would give an inverted image. Hence, light from the first prism is allowed to fall on a similar second prim which would again give a ${180}^o$ angle of deviation and make the image erect. Thus, it allows great magnification in a small space.