question_answer

Directions (Q. No. 1 to 5)

Read the following text and answer the following questions on the basis of the same:

In one of his experiments on interference, August Jean Fresnel used a biprism to induce interference between two beams. He split a diverging beam of light into two parts by using the biprism to refract them. This resulted in two split beams which acted as if they were from two coherent sources and which therefore interfered with each other.

A Fresnel Biprism is a thin double prism placed base to base and have very small refracting angle (\[{{0.5}^{o}}\]). This is equivalent to a single prism with one of its angle nearly \[{{179}^{o}}\] and other two of \[{{0.5}^{o}}\] each.

In Young's double Slits experiment, a single source is split in two coherent sources. For the Young's slits experiment, we must approximate that the slits act as point sources. This however is not the case, since the slits have finite width. In this way, it gives rise to unwanted diffraction effects that causes errors.

The Fresnel biprism experiment overcomes this problem.

A Fresnel biprism is a variation of Young's Slits experiment. When monochromatic light through a narrow slit falls on biprism that divides it into two components. One of these component is refracted from upper portion of biprism and the other one refracted through lower portion. Two virtual coherent sources formed from the original source. In this case, two virtual coherent sources are point sources and replace slits in Young's experiment.

The Fresnel biprism is:

A) a combination of two prisms with their bases in contact.

B) a combination of two prisms with their refracting surfaces in contact

C) single prism

D) not a prism actually.