Mirage is an optical illusion observed in hot deserts. It is entirely caused by:
A. Scattering of light
B. Diffraction of light
C. Total internal reflection of light
D. Interference of light
Answer: Option C
Solution (By JKSSB Mock Tests)
In hot deserts, the sand heats the air immediately above it, making it less dense (optically rarer) than cooler air higher up. Light from a tall object (like the sky or a tree) traveling downwards passes from denser to rarer air layers, bending away from the normal. Eventually, the angle of incidence exceeds the critical angle, causing total internal reflection. The observer perceives this reflected light as a pool of water on the ground.
Explanation:
Water's high specific heat (4186 J/kg·K) means it absorbs/releases large heat with small temperature change. This stabilizes temperatures: in engines, water coolant absorbs heat without large ΔT; in organisms, it buffers against temperature fluctuations. Memory tip: 'High specific heat = thermal buffer; water moderates climate and body temperature'. This application question tests understanding of material properties, frequently appearing in competitive exams. Always link physical properties to real-world uses; competitive exams emphasize practical implications of physics concepts.
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