Q5. Give the characteristics or nature of light?
Ans. There are two theories about the nature of light.
- Wave Theory: According to this theory, light consists of electromagnetic waves which do not require a material medium for their propagation.The wavelength of visible light waves is very small (4 x 10-7 m to 8 x 10-7). Speed of light wave is very high. (3 x 108 m/s)
- Practical Theory: According to this theory, light is composed of particles which travel in a straight line at very high speed.
The elementary particle that defines light is the photon.
Some of the phenomena of light can be explained only if light is considered to be made up of waves. Example: Phenomena like diffraction, polarization and interference.
But some phenomenon of light can be explained only if light is though to be made up of particles. Example: The phenomena like reflection, refraction, casting of Shadows of objects by light.
Light has a dual nature. It exhibits the properties of both waves and particles depending on the situation it is in.
The modern theory of light called quantum theory of light that combines both the waves and particle models of light.