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CET Karnataka Engineering CET - Karnataka Engineering Solved Paper-2008

  • question_answer
    If a black body emits 0.5 J of energy per second when it is at \[{{27}^{o}}C\], then the amount of energy emitted by it when it is at \[{{627}^{o}}C\] will be

    A)  40.5 J                                   

    B)  162 J

    C)  13.5 J                                   

    D)  135 J

    Correct Answer: A

    Solution :

    According to Stefan's law.                 \[E\propto {{T}^{4}}\]                 \[\frac{{{E}_{1}}}{{{E}_{2}}}={{\left[ \frac{{{T}_{1}}}{{{T}_{2}}} \right]}^{4}}\]                 \[\frac{{{E}_{1}}}{0.5}={{\left[ \frac{273+627}{273+27} \right]}^{4}}\]                 \[{{E}_{1}}=0.5{{\left( \frac{900}{300} \right)}^{4}}\] \[\Rightarrow \]               \[{{E}_{1}}=40.5\,J\]


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