Abstract: Light is electromagnetic radiation within a certain portion of the electromagnetic spectrum. The word usually refers to visible light, which is visible to the human eye and is responsible for the sense of sight.[1] Visible light is usually defined as having wavelengthsin the range of 400–700 nanometres (nm), or 4.00 × 10−7 to 7.00 × 10−7 m, between the infrared (with longer wavelengths) and theultraviolet (with shorter wavelengths).[2][3]This wavelength means a frequency range of roughly 430–750 terahertz (THz).