A glass prism splits white light into different colours. This phenomenon is called dispersion of light by prism. Which one of the following statements is correct?

CONCEPT:

Dispersion of light:

• Dispersion of light is the phenomenon of splitting of a beam of white light into its constituent colours on passing through a prism.
• The band of seven colours so obtained is called the (visible) spectrum.
• The basic reason behind the dispersion of white light into seven different colours is because all the seven rays of light of different colours travel at different speeds through the glass prism. 
• The degree of refraction also can be said as the bending of each light ray depends upon their individual speed while passing through the prism. 
• All the different colours of light ray travel at different speeds in glass and so the angle of bending or angle of refraction of each light ray are different. 

EXPLANATION:

• As we know, the bending of light is inversely proportional to the wavelength of the light.  

\(Bending\;\alpha \;\frac{1}{{Wavelength}}\)

• Different colours bend differently on passing through a prism and the bending of colour depends on wavelength.
• Higher wavelengths bend less, whereas shorter wavelength bend more.

• Out of all violet has the least wavelength and hence it bends the most and red has the highest wavelength, so it bends the least. Therefore option 2 is correct.