Light is a form of energy that causes the sensation of vision. Different theories on the nature of light were proposed on the basis of the fact that energy can be transferred from one point to another, either by particle motion or by wave motion.
Following are the important properties of light –
- Light travels in a straight line.
- The speed of light is faster than sound. Light travels at a speed of 3 x 108 m/s.
- Reflection of light
Reflection is the phenomenon in which light travelling in one medium, incident on the surface of another returns to the first medium, obeying the laws of reflection. According to the laws of reflection
- The incident ray, the reflected ray and the normal to the surface at the point of incidence all lie in the same plane.
- The angle of incidence is equal to the angle of reflection.
- Refraction of light
Refraction is a phenomenon in which there is a change in the speed of light as it travels from one medium to another and there is a bending of the ray of light. The refracted ray obeys the following laws.
- The incident ray, the refracted ray and the normal to the surface at the point of incidence all lie in the same plane.
- For the given pair of media and for the light of the given wavelength, the ratio of the sin of the angle of incidence to the sin of the angle of refraction is always a constant.
- Dispersion of light
The splitting of a ray of white light into its constituent colours is called dispersion.
- Diffraction of light
The phenomenon of bending of light around corners of small obstacles and hence it’s encroachment into the region of the geometrical shadow is called diffraction.
- Polarisation of light
Normal light vibrates in all directions perpendicular to the propagation of light. If the light is constrained to vibrate in only one particular plane, then the light is called polarised light. The phenomenon is called polarisation.
- Interference of light
Interference is the phenomenon of modification in the intensity of light due to redistribution of light energy in the region of superposition of two or more light waves.