Question

'Danger' signal lights are red in colour.

Hint:

Red light is used for danger signals because it has the longest wavelength and can be seen from a longer distance with minimal scattering.

Answer 1

Red light's extended wavelength, the greatest among visible colors, enables it to traverse greater distances with less scattering.
This enhanced visibility makes red light highly noticeable even in fog or rain, explaining its use in danger signals.Therefore, red is used for danger signals because it travels farther and is more visible, especially in conditions of low visibility.