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 source is turned off. The sample completely solidifies in time t seconds.

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 source is turned off. The sample completely solidifies in time t seconds. The specific latent heat of fusion of the substance is :

TestHub · Accepted Answer

At the melting point the input power just balances the heat loss, so the sample loses heat at rate P. In time t it releases heat Pt, which equals ML. Pt = M L ⇒ L = M Pt ​ . Answer: (B) Pt/M

Physics - Heat & Thermo Question with Solution | TestHub

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