Multiple choice

Red light is used for danger signals because it _____.

  1. is absorbed least by air

  2. is soothing to eye

  3. is scattered least

  4. has least chemical effect
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Red light has the longest wavelength in the visible spectrum, making it least susceptible to Rayleigh scattering by atmospheric particles like dust and water droplets. This property allows red light to travel longer distances with minimal dispersion, making it ideal for danger signals that need maximum visibility. Blue light scatters most, which is why the sky appears blue.

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