Question

why are danger signal lights red in colour

Answer 1

because the wave length of red colour is low than other colour that's why it scattered very low and could be seen from distance

Answer 2

hey friend,
here's your answer,

In the visible spectrum of light,the red light has the maximum wavelength and thus the maximum speed ,due to which it can travel far distances without much deviation even in dark or in presence of fog. therefore, red light can be see even from far distances and is best to be used in danger signal lights .

hope it helps you....!!