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JEE Main & Advanced Physics Thermometry, Calorimetry & Thermal Expansion Question Bank Critical Thinking

  • question_answer
    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]

    A)            \[\frac{Pm}{t}\]                  

    B)            \[\frac{Pt}{m}\]

    C)            \[\frac{m}{Pt}\]                  

    D)            \[\frac{t}{Pm}\]

    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   \[L=\frac{Pt}{m}\]


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