The light spectrum, also known as the electromagnetic spectrum, is the range of all possible frequencies of electromagnetic radiation.
The electromagnetic spectrum refers to the range of all electromagnetic radiation, which includes all types of light, radio waves, all the way to gamma rays. Electromagnetic radiation is a type of energy that travels through space in the form of waves. The electromagnetic spectrum is usually divided into different regions based on the wavelength or frequency of the radiation.
These regions, in order from longest to shortest wavelength, are:
- radio waves
- microwaves
- infrared radiation
- visible light
- ultraviolet radiation
- X-rays
- gamma rays
Visible light is the only part of the spectrum that can be detected by the human eye, and it is responsible for the colors we see in the world around us. The visible light portion of the electromagnetic spectrum is the range of electromagnetic radiation that can be detected by the human eye. It is a small portion of the overall electromagnetic spectrum and is located between the infrared and ultraviolet regions.
Visible light is made up of electromagnetic waves with wavelengths between approximately 400 ~ 700 nanometers (nm). The colors of the rainbow – red, orange, yellow, green, blue, indigo, and violet – are all part of the visible light spectrum, with red having the longest wavelength and violet having the shortest wavelength. The human eye is able to detect different colors of visible light thanks to specialized cells in the retina called cone cells. These cells contain pigments that are sensitive to different wavelengths of light, allowing us to see a wide range of colors.
Beyond the visible light spectrum, there are other types of electromagnetic radiation that are not visible to the human eye. These include radio waves, microwaves, infrared radiation, ultraviolet radiation, X-rays, and gamma rays, which all have different wavelengths and frequencies. While we cannot see these types of radiation with our eyes, we can use specialized equipment, such as radio antennas, X-ray machines, or thermal optics, to detect and measure them.