Physics
The figure given below, shows a thin beam of white light from a source S striking on one face of a prism.
(a) Complete the diagram to show the effect of the prism on the beam and to show what is seen on the screen.
(b) If a slit is placed in between the prism and the screen to pass only the light of green colour, what will you then observe on the screen?
(c) What conclusion do you draw from the observation in part (b) above?
Answer
(a) Below diagram shows the effect of the prism on the beam and the spectrum seen on the screen:
A coloured patch like a rainbow is seen on the screen. This is called the spectrum.
(b) When a slit is placed in between the prism and the screen to pass only the light of green colour then only green light is observed on the screen.
(c) With the help of the above experiment we can say that the prism does not produce colours, but it only splits the various colours present in the light incident on it.
Related Questions
(a) A beam of monochromatic light undergoes minimum deviation through an equiangular prism. How does the beam pass through the prism, with respect to its base?
(b) If white light is used in the same way as in part (a) above, what change do you expect in the emergent beam?
(c) What conclusion do you draw about the nature of white light in part (b)?
The diagram shown below, shows the path taken by a narrow beam of yellow monochromatic light passing through an equiangular glass prism. If the yellow light is replaced by a narrow beam of white light incident at the same angle, draw another diagram to show the passage of the white light through the prism and label it to show the effect of the prism on the white light.
Explain the cause of dispersion of white light through a prism.
Explain briefly, with the help of a neat labelled diagram, how does white light gets dispersed by a prism. On which surface of the prism, there is both the dispersion and deviation of light, and on which surface of the prism, there is only the deviation of light?