Question

In a science exhibition, boys of a Secondary school made two types of periscopes. In one of the periscopes, ordinary glass was used as the reflecting material, while in the other, a prism was used. When Anushka put her eyes on the eyepiece of the periscope, she saw that the image formed in one of the periscopes was quite bright, while in the other, it was a little blurred.

1. In which of the two periscopes, mirror or prism, Anushka saw the image brighter?
2. Why is one of the images brighter than the other?

Answer 1

1. Anushka saw the brighter image in the prism periscope.
2. A prism reflects light by total internal reflection, so almost all the light is reflected and very little is lost. An ordinary glass reflector does not reflect all the light; some light is lost by absorption and transmission. Therefore, the image formed by the prism is brighter and sharper.