Single correct option
Danger signals are made red mainly because red light
- A. has the shortest wavelength
- B. is scattered the most by air molecules
- C. is scattered the least by fog and dust
- D. has the highest speed in air
Show answer and solution
Answer: (C) is scattered the least by fog and dust
Scattering by small particles is stronger for shorter wavelengths. Red has the longest wavelength among visible colours, so it is scattered the least and travels farthest through fog or smoke. The speed of all colours in air is nearly the same.
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