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Q75
(NDA-I/2010)
Science & Technology › Basic Science (Physics, Chemistry, Biology) › Thermal physics
Answer Verified
A man with a dark skin, in comparison with a man with a white skin, will experience
Result
Your answer:
—
·
Correct:
D
Explanation
The correct answer is Option 4: more heat and more cold. This phenomenon is explained by the fundamental laws of thermodynamics, specifically Kirchhoff's Law of Thermal Radiation.
- Absorption of Heat: Darker skin contains higher concentrations of melanin, which acts as a more efficient absorber of radiant energy. According to physics, dark surfaces absorb more solar radiation than lighter surfaces, which reflect a significant portion. Thus, a dark-skinned man experiences more heat.
- Emission of Heat: According to Kirchhoff’s Law, a good absorber is also a good emitter. In colder environments, dark skin radiates internal body heat more rapidly than white skin. This higher rate of thermal emission causes the body to lose heat faster, leading to the sensation of more cold.
Therefore, because dark skin is both a superior absorber and a superior emitter of thermal radiation, it experiences greater intensity at both temperature extremes compared to white skin.
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