Light and its Properties

One branch of physics which is optics studies about light and its properties. A question asked about light is that – is it a wave or a particle? Well, a light is said to have a dual nature – it is a wave and it is a particle.

Light as a wave was explained by Thomas Young through his double-slit experiment. Based on the figure below, the individual slits acted as individual sources at which light passes through and spreads. (A thorough discussion about Young’s double-slit experiment is on a separate page.)

Light as a particle was explained by Albert Einstein through his photoelectric effect. This experiment made him won a Nobel prize. (A thorough discussion about photoelectric effect is on a separate page.)

Materials can be classified according to how they interact with light. There are opaque materials, which do not let light pass through them. In other words, they absorb light. Transparent materials allow light to easily pass through them. Translucent materials allow light to pass through them but distort the light as it pass through.

The light we see is the visible light. It is a part of the electromagnetic spectrum which is composed of different colors of light with different wavelengths. See figure below.

Light has various properties – reflection, refraction, dispersion, total internal reflection, interference, diffraction, scattering of light, and polarization. (A detailed discussion about the different properties of light will be on separate pages.)

Dispersion is the process in which light is separated into different colors due to the differences in degrees of refraction. An example of this is when light strikes through a prism, it will be separated into lights of different colors.

Total internal reflection happens when light is reflected totally at the boundary between two mediums.

Diffraction is defined as the bending of light waves around obstacles in its path. When light spreads out after passing through or by an opening or edge. For diffraction of light to occur, the opening must be very narrow.

When two light waves meet or coincide, it can create interference. Interference of light maybe constructive or destructive – depending on how the crests and troughs of the waves meet.