Which color of light has the longest wavelength?

Our eyes can see objects, which are light, but how much do we know about light? What are the characteristics of this thing that accompanies us every day?

In the visible light range, red light has the longest wavelength.

In fact, light is essentially an electromagnetic wave, so if infrared is also understood as light, then there is no such thing as light with the longest wavelength, because the wavelength of light has no maximum limit!

Introduction to light

Light is electromagnetic radiation. The wavelength range of this part of electromagnetic wave is approximately between 0.77 microns of red light and 0.39 microns of violet light. Electromagnetic waves with wavelengths above 0.77 microns to about 1000 microns are called "infrared". Those below 0.39 microns to about 0.04 microns are called "ultraviolet". Infrared and ultraviolet rays cannot cause vision, but optical instruments or photography methods can be used to measure and detect the presence of such luminous objects. Therefore, the concept of light in optics can also be extended to the infrared and ultraviolet fields. Even X-rays are considered to be light, and the visible light spectrum is only part of the electromagnetic spectrum. Light has wave-particle duality, that is, light can be regarded as an electromagnetic wave with a very high frequency ***1012~1015 Hz***, or light can be regarded as a particle, that is, a light quantum, or photon for short. Light is essentially an electromagnetic wave, covering a fairly wide range of the electromagnetic spectrum—from X-rays to far-infrared—but the wavelength is shorter than ordinary radio waves. Visible light that the human eye can see is only part of the entire electromagnetic spectrum. Light waves, including infrared rays, have shorter wavelengths and higher frequencies than microwaves. Therefore, it is a natural and inevitable trend to develop from microwave communications in electrical communications to optical communications.

Classification of light

Light is divided into artificial light and natural light. The reason why we can see the variegated and ever-changing scenes in the objective world is because our eyes receive the light emitted, reflected or scattered by objects. Light has a close relationship with human life and social practice.

Strictly speaking, light is a kind of radiation that can be observed by human eyes. Experiments have proven that light is electromagnetic radiation, and the wavelength range of this part of electromagnetic waves is approximately between 0.77 microns of red light and 0.39 microns of violet light. Electromagnetic waves with wavelengths above 0.77 microns to about 1000 microns are called "infrared". Those below 0.39 microns to about 0.04 microns are called "ultraviolet". Infrared and ultraviolet rays cannot cause vision, but optical instruments or photography methods can be used to measure and detect the presence of such luminous objects. Therefore, the concept of light in optics can also be extended to the infrared and ultraviolet fields. Even X-rays are considered to be light, and the visible light spectrum is only part of the electromagnetic spectrum.

Light has wave-particle duality, that is, light can be regarded as an electromagnetic wave with a very high frequency ***1012~1015 Hz***, or light can be regarded as a particle , that is, light quantum, referred to as photon.

Light is one of the sources of life on earth.

Light is the basis of human life. Light is a tool for humans to understand the external world. Light is the ideal carrier or communication medium for information.

According to statistics, at least 90% of the total information received by human sense organs from the external world passes through the eyes...

Light is essentially an electromagnetic wave, covering electromagnetic waves. The spectrum is a fairly wide range ranging from X-rays to far-infrared radiation, but the wavelengths are shorter than ordinary radio waves. Visible light that the human eye can see is only part of the entire electromagnetic spectrum.

When a beam of light is projected onto an object, phenomena such as reflection, refraction, interference, and diffraction will occur.

Light waves, including infrared rays, have shorter wavelengths and higher frequencies than microwaves. Therefore, it is a natural and inevitable trend to develop from microwave communications in electrical communications to optical communications. .

Ordinary light: Under normal circumstances, light is composed of many photons. In fluorescence, ordinary sunlight, lamplight, candlelight, etc., there is no connection between photons, that is, The wavelengths are different, the phases are different, the polarization directions are different, and the propagation directions are different. It is like an unorganized and undisciplined photon army. Each photon is a straggler and cannot act in unison.

Laser - a new world of optics

In the laser beam, all photons are related to each other, that is, their frequency or wavelength is consistent, the phase is consistent, and the polarization is consistent The direction is the same and the propagation direction is the same. The laser is like a well-disciplined photon army that acts in unison and therefore has extremely strong combat effectiveness. This is the main reason why lasers can do many things that sunlight, lights, and candlelight cannot.