Transmission Of Heat Question 74
Question: Surface of the lake is at 2°C. Find the temperature of the bottom of the lake
[Orissa JEE 2002]
Options:
A) $ 2^{o}C $
B) $ 3^{o}C $
C) $ 4^{o}C $
D) $ 1^{o}C $
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Answer:
Correct Answer: C
Solution:
A lake cools from the surface down. Above $ 4{}^\circ C, $ the cooled water at the surface flows to the bottom because of it’s greater density. But when the surface temperature drops below $ 4{}^\circ C $ (here it is $ 2{}^\circ C $ ), the water near the surface is less dense than the warmer water below. Hence the downward flow ceases, the water at the bottom remains at $ 4{}^\circ C $ until nearly the entire lake, is frozen.
BETA
