Question

Fig. 8.1 shows parallel wavefronts of a light wave in ice. The wavefronts are incident on a boundary with air. What is the phenomenon that occurs when a wave passes from one medium to another?

1) Reflection
2) Refraction
3) Diffraction
4) Interference

Answer 1

The phenomenon where light waves change direction when passing from one medium to another, such as from ice to air, is called refraction. This occurs due to changes in light speed caused by different densities of the media, explained by Huygens's principle and Snell's law.

Step-by-step explanation:

The phenomenon that occurs when a wave passes from one medium to another, such as light waves travelling from ice to air, is known as refraction. Refraction happens because the speed of light changes as it moves between mediums with different densities. This change in speed results in a change of direction of the light wave. Huygens's principle helps explain refraction by showing how each point on a wavefront acts as a source of secondary wavelets, leading to a new wavefront that bends at the interface between mediums. This bending of light is governed by Snell's law, which can be derived from Huygens's principle and the differences in the refractive indices of the two media.