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WB JEE Medical WB JEE Medical Solved Paper-2007

  • question_answer
    An immersion heater with electrical resistance \[\text{7}\Omega \] is immersed in 0.1 kg of water at \[\text{20}{{\,}^{\text{o}}}\text{C}\] for 3 min. If the flow of current is 4 A, what is the final temperature of the water in ideal conditions? (Specific heat capacity of water\[\text{=}\,\text{4}\text{.2}\times {{10}^{3}}\,JK{{g}^{-1}}{{K}^{-1}}\])

    A)  \[\text{28}{{\,}^{\text{o}}}\text{C}\]                                    

    B)  \[\text{48}{{\,}^{\text{o}}}\text{C}\]

    C)  \[\text{52}{{\,}^{\text{o}}}\text{C}\]                                    

    D)  \[68{{\,}^{\text{o}}}\text{C}\]

    Correct Answer: D

    Solution :

                     \[{{i}^{2}}Rt=ms\Delta t\] \[\Rightarrow \]\[{{(4)}^{2}}\times 7\times 3\times 60=0.1\times 4.2\times {{10}^{3}}\]                                 \[\times \,[T-(20\,+273)]\] \[T=341\,K=68{{\,}^{o}}C\]


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