Why do traffic lights use three colors of red, green and yellow?
Traffic lights are an important part of traffic signal command. Red means no passage, green means passage, and yellow means warning. These three colors were picked up all over the country, and also used in traffic signals, and have continued to this day. Be familiar with and obey the traffic rules.
In optics, the wavelength of red light is almost the longest. The ability to travel through the air is also greatest, with red signals more noticeable than others. The red light was therefore chosen as the no-pass signal.
That is, because red attracts more attention. Red is also widely used in people's life. A shopping mall and store doors will use red fonts to advertise, that is, to attract people's attention and play the effect of advertising. If you take your child to the streets and alleys, you will see red jumping red letters on the store doors.
Red and green have the most color difference and are easy to tell apart. At the same time, the light display distance of the green signal is also farther. Therefore, the green signal light is used as a pass signal. Pedestrians and vehicles pass when the light at the intersection is green. It is also convenient for pedestrians and vehicles to distinguish signal indications and respond in time.
The wavelength of the yellow signal has a relatively strong penetrating ability. Use the yellow signal as a warning. When the yellow light is on, it warns the vehicle that the red light is about to turn on and wait outside the line. If the vehicle has already crossed the line or is inconvenient to stop, it can pass in time. The yellow light signal illuminates to remind pedestrians to pass quickly or back to the original place to wait for the red light. It has the effect of warning pedestrians and vehicles.
The yellow signal is the most visible and the most conspicuous. Especially vehicles that drive at night. There is a yellow warning sign ahead, which the driver can see for the first time. Therefore, many cars or dangerous objects parked on the side of the road have yellow signs as warnings.