Question

Huygens’s wave theory is used:

A. To determine the velocity of light
B. To find the position of wave front
C. To determine the wavelength of light
D. To find local length of a lens

Answer 1

Hint: It states that each point of the wavefront is the source of the secondary wavelets which spread out in all directions with the speed of a wave. So if we consider a point source, it will emit its wavefront and the nature of the wavefront will be a spherical one.

Complete answer:
Huygens’s principle, in optics, a statement that all points of a wave front of light in a vacuum or transparent medium may be regarded as new sources of wavelets that expand in every direction at a rate depending on their velocities. it is a powerful method for studying various optical phenomena.

Huygens proposed a hypothesis for the geometrical construction of the position of a common wavefront at any instant during the propagation of waves in a medium.

Therefore, the correct choice is: (B) To find the position of the wave front.

Note:
The Huygens’s wave theory is that all points on a wave front of light are sources of secondary waves that surfaces tangential to these waves define the position of the wave front at any point in time. He found that light propagates in the form of waves and needs a medium to propagate in all possible directions. He gave a hypothetical medium which is known as ether .