Question

Fig shows a thin beam of white light from a source S striking on one face of a prism.

1. Complete the diagram to show the effect of the prism on the beam and to show what is seen on the screen.
2. 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?
3. What conclusion do you draw from the observation in part (b) above?

Answer 1

1. On the screen are seven colors arranged in the sequence of "VIBGYOR." The other colors are arranged as in VIBGYOR, with Red at the top and Violet at the bottom.
   
2. 
   
   We will observe the light of only green colour on the screen.
3. We draw the conclusion that a prism by itself produces no colours.