Nature Of Light

Oarticle Nature of Light (Newton's Corpuscular Theory):

According to Newton, light travels in space with a great speed as a stream of very small particles called corpuscles.

This theory was failed to explain interference of light and diffraction of light. So wave theory of light was discovered.

Wave Nature of Light:

Light waves are electromagnetic waves so there is no need of medium for the propagation of these waves. They can travel in vacuum also. The speed of these waves in air or in vacuum is maximum i.e., 3´ 10⁸ m/s. Photoelectric effect was not explained with the help of wave theory, so Planck gave a new theory which was known as quantum theory of light.

Quantum Theory of Light:

When light falls on the surface of metals like caesium, potassium etc., electrons are given out. These electrons are called 'photo-electrons' and phenomenon is called 'photo-electric effect'.

Reflection of light

When light travels in the same homogeneous medium; it travels along a straight path. However, when it passes from one transparent medium to another, the direction of its path changes at the interface of the two media. This is called refraction of light.