BVP Medical BVP Medical Solved Paper-2012

  • question_answer
    The surface temperature of the sun is T K and the solar constant for a plate is S. The sun subtends an angle 9 at the planet. Then,

    A)  \[{{427}^{o}}C\]                              

    B)  \[{{27}^{o}}C\]

    C)  \[0.52\]                              

    D)  \[0.31\]

    Correct Answer: A

    Solution :

                    Let radius of sun = R Distance of earth from the sun = d Power radiated from the sun                                 \[=(4\pi {{R}^{2}})\sigma {{T}^{4}}=P\] Energy received/area/s \[=S=\frac{P}{4\pi {{d}^{2}}}\] \[=4\pi {{R}^{2}}\sigma \frac{{{T}^{4}}}{4\pi {{d}^{2}}}=\sigma {{T}^{4}}\frac{{{R}^{2}}}{{{d}^{2}}}=\frac{1}{4}\sigma {{T}^{4}}{{\left( \frac{2R}{d} \right)}^{2}}\] Angle subtended by sun at earth                                 \[\alpha =\frac{2R}{d}\] S = constant \[\times {{T}^{4}}\times {{\alpha }^{2}}\]                                 \[S\propto {{T}^{4}}\]


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