JEE Main & Advanced Physics Transmission of Heat Question Bank Critical Thinking

  • question_answer
    A hot metallic sphere of radius \[r\] radiates heat. It's rate of cooling is

    A)            Independent of \[r\]        

    B)            Proportional to \[r\]

    C)            Proportional to \[{{r}^{2}}\]  

    D)            Proportional to \[1/r\]

    Correct Answer: D

    Solution :

                       Rate of cooling \[{{R}_{C}}=\frac{d\theta }{dt}=\frac{A\varepsilon \sigma ({{T}^{4}}-T_{0}^{4})}{mc}\]            Þ \[\frac{d\theta }{dt}\propto \frac{A}{V}\propto \frac{{{r}^{2}}}{{{r}^{3}}}\] Þ \[\frac{d\theta }{dt}\propto \frac{1}{r}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner