Case: In an experiment, Pooja used a equilateral triangular glass prism and projected a narrow beam of white light source from one side of the surface of the prism. She placed a screen on the other side and saw many colours appearing as patches on the screen. But when she used a red light source, she could only see a red patch on the screen. Similarly she used a blue and green light source and could only see one colour patch on both occasions.

58- The reason why she could no see any other colour when the red light was used was because:
A. Red colour does not refract in prism.
B. Red colour is monochromatic.
C. The prism was defective.
D. The prism is opaque to red colour

Dear student,

When white light goes through a prism, it gets dispersed into its components, that's why you can see a spectrum on the screen.
But while we use any monochromatic light, instead of white light, on the screen we can only see that monochromatic light only.
So, from this concept, we can conclude that red is a monochromatic colour.

Option B is the correct answer

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