What happens when the sunlight travels through the Earth's atmosphere ?
- A.The blue colour is scattered more compared to the red colour
- B.The red colour is scattered more compared to the blue colour
- C.Both the blue and the red colours are scattered equally
- D.The blue colour is not scattered but the red colour is scattered the most
Correct answer
Explanation
The correct answer is A, the blue colour is scattered more compared to the red colour. Tiny gas molecules in the air scatter short wavelengths far more strongly than long ones.
This is Rayleigh scattering: the amount of scattering varies inversely with the fourth power of the wavelength. Blue light has a wavelength of roughly 450 nm and red light roughly 700 nm, so blue is scattered several times more than red. The scattered blue light reaches our eyes from every part of the sky, which is why the clear sky looks blue. At sunrise and sunset sunlight crosses a much thicker layer of air, most of the blue is scattered away, and the Sun looks red or orange.
B is wrong because red, having the longest wavelength of visible light, is scattered the least. C is wrong because scattering depends on wavelength, so the two colours are not scattered equally. D is wrong because blue is scattered the most and red the least.
Exam tip: shorter wavelength, more scattering: blue sky by day, red Sun at sunrise and sunset.
Practice Questions
View allThe fact that the planets move around the Sun, not in circles but in ellipses, was first demonstrated by
- A.Galileo
- B.Martin Luther
- C.Johannes Kepler
- D.Copernicus
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In 1609 Kepler showed that the planets move around the Sun in elliptical orbits, with the Sun at one focus of the ellipse.
Read the full explanation →Which one of the following statements is correct?
- A.Urea is produced in liver.
- B.Urea is produced in blood.
- C.Urea is produced from digestion of starch.
- D.Urea is produced in lung and kidney.
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Read the full explanation →Which one of the following is the correct sequence of passage of light in a compound microscope?
- A.Condenser-Objective lens-Eyepiece-Body tube
- B.Objective lens-Condenser-Body tube-Eyepiece
- C.Condenser-Objective lens-Body tube-Eyepiece
- D.Eyepiece-Objective lens-Body tube-Mirror
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Light passes through the condenser to the specimen, is picked up by the objective lens, travels up the body tube and reaches the eye through the eyepiece.
Read the full explanation →Which one of the following statements regarding haemoglobin is correct?
- A.Haemoglobin present in RBC can carry only oxygen but not carbon dioxide.
- B.Haemoglobin of RBC can carry both oxygen and carbon dioxide.
- C.Haemoglobin of RBC can carry only carbon dioxide.
- D.Haemoglobin is only used for blood clotting and not for carrying gases.
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Read the full explanation →Which one of the following statements regarding histone proteins is correct?
- A.Histones are proteins that are present in mitochondrial membrane.
- B.Histones are proteins that are present in nucleus in association with DNA.
- C.Histones are proteins associated with lipids in the cytosol.
- D.Histones are proteins associated with carbohydrates in the cytosol.
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They are the proteins around which DNA winds to form chromatin in the nucleus of eukaryotic cells. Histones are small basic proteins, rich in the positively charged amino acids lysine and arginine, which attract the negatively charged phosphate groups of DNA.
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