Red colour is used for danger signals because

Correct option is B

Correct Answer: B. It undergoes least scattering

• Red light has the longest wavelength among visible light (~620-750 nm).

• Because of its long wavelength, red light undergoes least scattering by particles in the atmosphere (Rayleigh scattering).

• This allows red light to travel longer distances clearly, making it highly visible even in fog, smoke, or dust.

• This visibility is why red is used for danger signals, stop signs, and warning lights.

• Other colors like blue or violet have shorter wavelengths and scatter more, making them less visible at a distance.

• The psychological association of red with danger/fear is culturally reinforced but not the primary physical reason.

• Red’s high visibility in poor conditions makes it ideal for safety and alert signals in:

  • Traffic lights

  • Emergency vehicles

  • Warning signs