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?

(a) The seven colours of the spectrum in order are Violet, Indigo, Blue, Green, Yellow, Orange and Red.

(b) No, all the seven colours have different widths in the spectrum.

(c) Violet colour of the white light is deviated the most, as it's wavelength is least i.e., 4000 Å and Red colour of the white light is deviated the least, as it's wavelength is the longest i.e., 8000 Å.