Wave theory of light

Wave theory of Light

The wave theory of light was proposed by Huygen in 1678.

The main features of Huygen’s wave theory of light are as follows:

1. According to Huygen, light is propagated in the form of waves.
2. The waves are emitted from a source of light and travel with a very high velocity.
3. The waves can propagate in all possible directions with a constant velocity in a homogeneous medium.
4. When these waves enter our eyes, we get the sensation of light.
5. The different colors of light are due to the different wavelengths of the light waves.
6. To explain propagation of light through vacuum, Huygen assumed that there exist a hypothetical medium called as ether and light can propagate through ether.

Merit’s of Huygen’s wave theory:

1. On the basis of wave theory, phenomenon of reflection and refraction can be satisfactorily explained.
2. The application of wave theory to refraction concludes that the velocity of light in a rarer medium is greater than the velocity of light in a denser medium.
3. Several phenomena of light such as double refraction, interference diffraction of light can be satisfactorily explained on the basis of wave theory.

Demerit’s of Huygen’s wave theory:

1. Rectilinear propagation of light cannot be explained on the basis of the wave theory of light.
2. Several phenomena of modern physics such as photoelectric effect, Compton effect cannot be explained on the basis of the wave theory of light.
3. For the propagation of light through vacuum, Huygen assumed presence of ether medium. But such medium does not exist.
4. Huygens wave theory initially could not explain polarization light.