Humans can sense visible light, which consists of a specific range of electromagnetic wavelengths. Visible light spans a range of approximately 400 to 700 nanometers (nm). Within this range, humans perceive different colors, such as red, orange, yellow, green, blue, indigo, and violet.
However, humans cannot naturally perceive ultraviolet (UV) or infrared (IR) light without the aid of technological devices.
Ultraviolet (UV) light: UV light has shorter wavelengths than visible light, ranging from approximately 10 nm to 400 nm. Humans have limited sensitivity to certain longer-wavelength UVA (315-400 nm) and shorter-wavelength UVB (280-315 nm) light, but these wavelengths are not directly perceived as colors by humans. Prolonged exposure to certain UV wavelengths can be harmful to the eyes and skin.
Infrared (IR) light: IR light has longer wavelengths than visible light, typically ranging from around 700 nm to 1 millimeter. Humans do not have natural sensory receptors to directly perceive IR light. However, humans can indirectly sense the thermal effects of IR light as heat.
It's worth noting that some animals, such as certain insects, birds, or reptiles, have the ability to perceive UV or IR light due to specialized visual systems or sensory organs. Additionally, technological devices like UV or IR cameras can be used to visualize and detect these types of light for scientific or practical purposes.