INSIGHT UPSC QUIZ

Science & Technology General Science
Q.

Consider the following statements: 

1. The ‘danger’ signal lights are red in colour as the red is least scattered by fog or smoke.

2. The sky appears dark to passengers flying at very high altitudes because of scattering of light. 

Which of the statements given above is/are correct?

Explanation:

ANSWER: (A) 

  • The earth’s atmosphere is a heterogeneous mixture of minute particles. These particles include smoke, tiny water droplets, suspended particles of dust and molecules of air. 
  • When a beam of light strikes such fine particles, the path of the beam becomes visible and this phenomenon is called the scattering of light. The colour of the scattered light depends on the size of the scattering particles. Very fine particles scatter mainly blue light while particles of larger size scatter light of longer wavelengths. 
  • The ‘danger’ signal lights are red in colour as the red is least scattered by fog or smoke. (Thus, Statement 1 is correct)
  • The sky appears dark to passengers flying at very high altitudes, as scattering is not prominent at such heights. (Thus, Statement 2 is correct)

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