Properties Of Solids And Liquids Question 106
Question: A substance of mass m kg requires a power input of P watts to remain in the molten state at its melting point. When the power is turned off, the sample completely solidifies in time t sec. What is the latent heat of fusion of the substance [IIT JEE 1992]
Options:
A) $ \frac{Pm}{t} $
B) $ \frac{Pt}{m} $
C) $ \frac{m}{Pt} $
D) $ \frac{t}{Pm} $
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Answer:
Correct Answer: B
Solution:
Heat lost in t sec = mL or heat lost per sec = $ \frac{mL}{t} $ .
This must be the heat supplied for keeping the substance in molten state per sec.
$ \frac{mL}{t}=P $ or $ L=\frac{Pt}{m} $
