Light is defined as the electromagnetic radiation with wavelengths between 380 and 750 nm which is visible to the human eye.
Electromagnetic radiation, such as light, is generated by changes in movement (vibration) of electrically charged particles, such as parts of ‘heated’ molecules, or electrons in atoms (both processes play a role in the glowing filament of incandescent lamps, whereas the latter occurs in fluorescent lamps).
Light is indispensable to life on the planet and consequently affects humans and other creatures alike.
Notably there are important physical effects through the interaction of light with our skin and our eyes leading to the ‘warm’ (red light) and ‘cold’ (blue light) sensation as well as the side effects through our accommodation to the periodic changes each day and with the season which contribute to the regulation of activity/rest cycles.
Light is a form of electromagnetic radiation that enables the human eye to see or make things visible. It is also defined as radiation that is visible to the human eye. Light contains photons, which are minute packets of energy.
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
Light is a transverse wave and does not need any medium to travel.
Light does not need a material medium to travel. That is, it can travel through a vacuum too. Scientists have assigned a value of 299, 792, 458 m/s to the speed of light in a vacuum.
The wavelength (λ) of light changes when it goes from one medium to another.
Light undergoes refraction (bending) when it travels from one transparent medium to another.