What is the wavelength range of visible light and ultraviolet light?

Visible light wavelength range: 400-760nm.

UV wavelength range: below 400nm.

Visible light is the part of the electromagnetic spectrum that can be perceived by the human eye. There is no precise range in the visible spectrum; the wavelength of electromagnetic waves that the average human eye can perceive is between 400 and 760nm, but some people can perceive it. Electromagnetic waves with wavelengths approximately between 380 and 780nm.

Ultraviolet light is a general term for radiation with wavelengths from 0.01 to 0.40 microns in the electromagnetic spectrum, which cannot cause human vision. Radiation with a wavelength of 0.01~0.4 microns in the electromagnetic spectrum, ranging from the visible violet end to X-rays. Has sterilizing function.

Extended information:

Visible light is the part of the electromagnetic spectrum that the human eye can perceive. There is no precise range in the visible spectrum; the wavelength of electromagnetic waves that the average human eye can perceive is between 400 and 760nm. time, but there are still some people who can perceive electromagnetic waves with wavelengths between approximately 380 and 780nm.

The human eye with normal vision is most sensitive to electromagnetic waves with a wavelength of about 555nm, which is in the green light region of the optical spectrum. The range of light that the human eye can see is affected by the atmosphere. The atmosphere is opaque to most electromagnetic radiation, with the exception of visible light bands and a few others, such as radio communication bands.

Many other organisms can see different ranges of light waves than humans. For example, some insects, including bees, can see ultraviolet waves, which is very helpful in finding nectar. A recent study found that visible light may also be able to "see through" the physical body.

Visible light radiation generally refers to the radiation in the 0.38-0.76 micron spectrum band of the solar radiation spectrum, which is composed of seven colors of light, including purple, blue, cyan, green, yellow, orange, and red. It is necessary and effective solar radiation energy for green plants to carry out photosynthesis. The visible radiation reaching the Earth's surface varies with atmospheric turbidity, solar altitude, cloud cover, and weather conditions. Visible light radiation accounts for about 45 to 50% of the total radiation.

Ultraviolet light is electromagnetic radiation with a shorter wavelength than visible light but longer than X-rays. Ultraviolet light has a wavelength range of 10-400 nm in the electromagnetic spectrum. This range begins at the short wavelength limit of visible light and overlaps with the longer wavelengths of X-rays. Ultraviolet light is divided into A rays, B rays and C rays (referred to as UVA, UVB and UVC), with wavelength ranges of 400-315nm, 315-280nm and 280-190nm respectively.

Function 1: Sterilization

This is the most common function of ultraviolet rays. Since ultraviolet rays have strong lethality to living things, humans use it to deal with these difficult bacteria and viruses. We also often use sunlight to help us sterilize. However, special attention should be paid to the fact that these sterilization equipment can also harm the human body, so you must be particularly careful when using them.

Function 2: Identification and perspective

Because ultraviolet rays are more penetrating than ordinary visible light, scientists often use ultraviolet rays for perspective or identification work (just like using X-rays Come for a health check). For example, ultraviolet light can be used to check fine cracks in metal, the authenticity of pictures, food safety, and even when exploring space, ultraviolet light can come in handy.

Function 3 Health and Medical

Excessive exposure to ultraviolet rays can cause harm to the human body, but appropriate sunlight can help the body synthesize vitamin D.

Recently, it has been discovered in medicine that irradiating an appropriate amount of A light or B light can also treat skin lesions such as psoriasis and white spots, so that patients no longer have "itchy skin". However, this "light therapy" can only be performed under the instruction of a physician, because excessive exposure may cause side effects or permanent damage to some people.

Function 4: Guiding the way for insects

Since each creature can receive a different range of light frequencies, some animals have to rely on ultraviolet light to find their way or see objects clearly. For example, bees must also use ultraviolet light when searching for nectar and pollinating flowers. In addition, ultraviolet rays can also assist plants in photosynthesis.

Reference materials: Baidu Encyclopedia - Ultraviolet light? Baidu Encyclopedia - Visible light