NEET Physics Transmission of Heat NEET PYQ-Transmission Of Heat

  • question_answer
    A black body at \[{{1227}^{o}}C\] emits radiations with maximum intensity at a wavelength of \[5000\text{ }{\AA}\]. If the temperature of the body is increased by \[{{1000}^{o}}C,\] the maximum intensity will be observed at:                                                                                                                                                          [AIPMT (S) 2006]

    A)  \[4000\text{ }{\AA}\]

    B)                   \[5000\text{ }{\AA}\]

    C)  \[6000\text{ }{\AA}\]

    D)                   \[3000\text{ }{\AA}\]

    Correct Answer: D

    Solution :

    Key   Idea: The product of wavelength corresponding to maximum intensity of radiation and temperature of the body in Kelvin is constant. According to Wien's law
    \[{{\lambda }_{m}}T=\]= constant (say b)
    where \[{{\lambda }_{m}}\] is wavelength corresponding to maximum intensity of radiation and T is temperature of the body in Kelvin.
    \[\therefore \]      \[\frac{{{\lambda }_{m'}}}{{{\lambda }_{m}}}=\frac{T}{T'}\]
    Given,   \[T=1227+273=1500\,K,\]        
                \[T'=1227+1000+273=2500\,K\]
                \[{{\lambda }_{m}}=5000\,{\AA}\]
    Hence,  \[{{\lambda }_{m'}}=\frac{1500}{2500}\times 5000=3000\,{\AA}\]


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