What is the cause of dispersion of white light through a glass prism ? Draw a ray diagram to show the path of light when two identical glass prisms are arranged together in inverted position with respect to each other and a narrow beam of white light is allowed to fall obliquely on one of the faces of the prisms.
The speed of light rays different colours remains same in vaccum and air but in any other medium light rays travel with the different speed and bend through the different angles, which leads to the dispersionof light.
Newton found that the dispersion of light can be reversed. He kept two prisms close to each other one in erect position and other in inverted position.
The light gets dispersed when passes through the first prism.
The second prism takes all seven coloured rays from the first prism and recombines those rays into white light. it shows that the sunlight is made up of seven colour.
These activities can be explained by the diagram as follows: