In the dispersion of white light by a common glass prism, which one among the following is correct?

The correct answer is option "4"

Concept:

• Dispersion of light is the phenomenon of splitting a beam of white light into its constituent colors on passing through a prism.
• The band of seven colors so obtained is called the (visible) spectrum.
• The basic reason behind the dispersion of white light into seven different colors is because all the seven rays of light of different colors 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 colors 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:

• In a glass prism, the refractive index is higher for shorter wavelengths (blue light) compared to longer wavelengths (red light).
• This means that blue light slows down more and deviates more from its original path than red light when entering and exiting the prism.