Name the seven prominent colours of the white light spectrum in order of their increasing frequencies.

The wavelengths for the light of red and blue colours are nearly 7.8 x 10^-7 m and 4.8 x 10^-7 m respectively.

(a) Which colour has the greater speed in vacuum?

(b) Which colour has greater speed in glass?

What do you understand by the term spectrum?

A ray of white light is passed through a glass prism and a spectrum is obtained on a screen.

(a) Name the seven colours of the spectrum in order.

(b) Do the colours have the same width in the spectrum?

(c) Which colour of the spectrum of white light deviates (i) the most? (ii) the least?