The visible spectrum refers to the range of wavelengths of electromagnetic radiation that can be detected by the human eye, resulting in the perception of various colors. The visible spectrum spans approximately from 400 to 700 nanometers (nm) in terms of wavelength.
Within the visible spectrum, different colors are associated with specific ranges of wavelengths. These colors, in order from shortest to longest wavelength, are violet, blue, green, yellow, orange, and red. Violet has the shortest visible wavelength at around 400 nm, while red has the longest visible wavelength at approximately 700 nm.
Outside the visible spectrum, there are wavelengths that are considered invisible to the human eye. These include both shorter and longer wavelengths than those in the visible range.
Shorter wavelengths than the visible range include ultraviolet (UV) radiation. UV radiation has wavelengths shorter than 400 nm and is invisible to the human eye. However, some animals, such as bees and certain birds, can detect UV light.
Longer wavelengths than the visible range include infrared (IR) radiation. IR radiation has wavelengths longer than 700 nm and is also invisible to the human eye. However, certain types of IR radiation, known as near-infrared (NIR), have wavelengths closer to the visible range and can be detected by specialized cameras or sensors.
Beyond UV and IR radiation, there are other forms of electromagnetic radiation such as X-rays and gamma rays, which have even shorter wavelengths than UV radiation, and radio waves, which have longer wavelengths than IR radiation. These types of radiation are also invisible to the human eye.
In summary, the visible spectrum spans from approximately 400 to 700 nm and encompasses the colors that we can perceive. Wavelengths shorter than the visible range, such as UV radiation, and longer wavelengths, such as IR radiation, are considered invisible to the human eye. Other forms of electromagnetic radiation, such as X-rays, gamma rays, and radio waves, are also invisible to the human eye due to their respective wavelength ranges.