Question

why red signals are used as a danger sign ? Explain

Answer 1

due to longer wavelength it diverges less than any other colour due to which it can be seen from far

Answer 2

because that the receptors for red colours in the eye are clustered in the area near the centre where the sharpest images are formed. A biologist's answer is that nature uses red as a warning colour because it stands out most vividly against a green background. Other answers are that we associate it with danger because it is the colour of fire and blood. Maybe this last answer is nearest to the mark if we go by the behaviour of elephants, who go ballistic when they see the colour red - not unreasonably, since it is the colour worn by Maasai warriors, who love to demonstrate their virility by spearing the creatures. That said, warning signs in China have black borders on a yellow background, so red isn't always the first choice for signalling danger.

______swarnim ___####