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Red light stop, green light go
- Oct 03, 2018 -

Why are traffic signals red, yellow and green at city intersections and railway lines? This is determined by research and practice and by the principle of optics.

Of the seven colors red, orange, yellow, green, green, blue and purple, the red light wave is the longest. The longer the wave, the greater its ability to penetrate the surrounding medium. So under the same lighting conditions, red appears far away, and people are more sensitive to the feeling of red. So red is used as a stop signal.

Yellow orange light is second only to red light in wavelength. Yellow glass is used as a slow signal because of its ability to penetrate light and its distance.

The wavelength of green light is a kind of longer color light except red, orange and yellow, and the distance is also far, and the difference between green and red is easy to distinguish, so it is adopted as the traffic signal.

Author:Bunny Sun