Why do car fog lights use yellow light instead of eye-catching red light!

What car fog light uses yellow light? Because the human eye is most sensitive to yellow-green light. In fact, the color used in automotive lamps has little to do with scattering factors, because the degree of Mie scattering that occurs in heavy fog has nothing to do with the wavelength of incident light.

● What color of the human eye is most sensitive to

The purpose of the lamps installed in the car is to be alert, so it is necessary to find out what color the human eye is most sensitive to. The sensitivity of the optic nerve to different wavelengths of light is different. It is most sensitive to green light and the least sensitive to red and blue light. The International Commission on Illumination (CIE) has determined the relative sensitivity of the human eye to various wavelengths of light based on experimental results.

In the case of bright vision, that is, when the brightness is greater than 3 cd / m2, the sensitive wavelength of the human eye, that is, the peak wavelength of the spectral light visual efficiency corresponds to a wavelength of 555 nm, which belongs to yellow-green light.

In the case of scotopic vision, that is, when the brightness is less than 0.001 cd / m2, the sensitive wavelength of the human eye is at 507 nm.

Yellow wavelength: 540 ~ 600nm, green wavelength: 495nm ~ 540nm, cyan: 460 ~ 495nm.

So the fog light uses yellow light, which is very reasonable. So why does the brake light use a red light? That is the meaning that red is dangerous for human beings. In fact, the human eye is not sensitive to it.