What is a prism ? Draw a neat diagram to show refraction of a light ray through a triangular glass prism. Define angle of deviation.

What is a prism ? Draw a neat diagram to show refraction of a light ra

1.	What is a prism ? Draw a neat diagram to show refraction of a light ray through a triangular glass prism. Define angle of deviation.
Answer» Solution :An optical PRISM has two TRIANGULAR bases and THREE rectangular lateral surfaces, which are inclined to each other. Angle between its two lateral faces is called the angle of prism. The labelled diagram has been shown in Fig. 11.5, in which `anglePEN=anglei`=angle of INCIDENCE, `angleN.EF= angler`=angle of refraction and `angleMRF= anglee=` angle of emergence Whenever refraction of light takes place through a prism, the emergent ray bends towards the BASE ofthe prism. The angle between the directions of incident ray and emergent ray is called the angle of deviation D.