Physics – 3.2.2 Refraction of light | e-Consult

Refraction from Air to Water:

Light refracts when it passes from air into water because the speed of light is different in air and water. Light travels slower in water than in air. When light travels from a medium with a lower refractive index (air) to a medium with a higher refractive index (water), it bends towards the normal (the line perpendicular to the surface). This bending is refraction.

Refractive Index and Wavelength:

The refractive index of a material is not constant; it varies with the wavelength of light. Generally, shorter wavelengths (e.g., blue light) are refracted more than longer wavelengths (e.g., red light). This is because the speed of light in a material is slightly different for different wavelengths. This difference in speed leads to different degrees of bending for different colours.

Dispersion of White Light:

White light is a mixture of all the colours of the visible spectrum. Because each colour has a different wavelength and therefore a different refractive index in a material, the different colours are refracted by different amounts. This difference in refraction causes the separation of white light into its constituent colours – this is called dispersion. The order of the colours in a spectrum is Red, Orange, Yellow, Green, Blue, Indigo, Violet (ROYGBIV), with red being refracted the least and violet being refracted the most.