Question

What is a spectrum ? How can we recombine the components of white light after a glass prism has separated them ? Illustrate it by drawing a diagram.

Answer 1

(I) When a beam of white light is passed through a glass prism, a band of seven colours is formed on a white screen. This band of seven colours is called spectrum of white light.




(1) Newton showed that the seven coloured lights of the spectrum can be recombined to give back white light.

(2) First he tried to split the colours of the spectrum of white light using a prism.

(3) He then placed a second identical prism in an inverted position with respect to rarer to a denser medium. So, due to these bent rays, the sun appears higher in the horizon that it actually is as shown in. Therefore the sun becomes visible about two minutes before its actural sunrise.

Answer 2

when white light falls on glass prism 8t spread out in 7 different colours and it can be clearly seen on white screen .
I hope it will be helpful for you.