Question

How would we split white light into its constituent colours ?

Answer 1

when it passes through a glass prism it splits  into its constituentspectrum of colors (i.e. violet, indigo, blue, green, yellow, orange and red).
splitting of colours is called as dispersion..

Answer 2

For doing so... we would pass through a prism, a glass prism to be precise... the white light will then get split into its constituent colours-
Violet
Indigo
Blue
Green
Yellow
Orange
Red