A report on Light, Spectrum, Wavelength and Electromagnetic spectrum

Light or visible light is electromagnetic radiation within the portion of the electromagnetic spectrum that is perceived by the human eye.

The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies.

Visible light is usually defined as having wavelengths in the range of 400–700 nanometres (nm), corresponding to frequencies of 750–420 terahertz, between the infrared (with longer wavelengths) and the ultraviolet (with shorter wavelengths).

The word was first used scientifically in optics to describe the rainbow of colors in visible light after passing through a prism.

As scientific understanding of light advanced, it came to apply to the entire electromagnetic spectrum.

This frequency range is divided into separate bands, and the electromagnetic waves within each frequency band are called by different names; beginning at the low frequency (long wavelength) end of the spectrum these are: radio waves, microwaves, infrared, visible light, ultraviolet, X-rays, and gamma rays at the high-frequency (short wavelength) end.

The primary properties of light are intensity, propagation direction, frequency or wavelength spectrum and polarization.

Examples of waves are sound waves, light, water waves and periodic electrical signals in a conductor.

The range of wavelengths or frequencies for wave phenomena is called a spectrum.

The name originated with the visible light spectrum but now can be applied to the entire electromagnetic spectrum as well as to a sound spectrum or vibration spectrum.

Soon the term referred to a plot of light intensity or power as a function of frequency or wavelength, also known as a spectral density plot.