Question

I've heard that the three primary colours (red, blue and green)also forms a white light. Then why do always prism disperses the white light into the seven colours?

Answer 1

Hi Antriksh!

The combination of primary colours gives white light. But, in case of sunlight, there are seven constituent colours. So, when the sunlight is dispersed by the prism, it splits up into the constituent colours. If a white light made by the three primary colours is dispersed by a prism, it will give the three constituent colours only.

Cheers!!