Traffic light color and their meaning.

Everyone must have heard about the traffic signal lights and their meaning. But did you ever think about color is that why red is to stop, yellow means wait and green means go. Why only those color? Why not blue, purple, white? These colors are selected according to their wavelength. Before moving further, Let's take a look at the history of traffic signals.

Earlier the traffic signals are not used for car, but they used for trains. They were red and greens gas-powered little dangerous when the event of leakage in out traffic signals there were 3 different colors used, they are as,

1)Red:

As you all should know that red is colors of dangerous. Red symbol is inherent from railroads. It has the longest wavelength of any color on the visible spectrum. That means you can see it from a great distance than the other colors.

2)Green:

Green color means cautions at first. Its wavelength is next to (and shorter than) yellow's on the visible spectrum. Thus, green became "go," and for a long time, railways used only green and red to signal trains.

3)Yellow: 

As materials and technologies evolved, the ability to produce highly reflective signs meant that red could  resume its natural spot in the sign hierarchy, leaving the still-highly-visible yellow (it's second only to red in  terms of visible wavelength) to the domain of "caution." that's why school zones and buses, crosswalks, and other important warnings are yellow today.