NEET NEET SOLVED PAPER 2018

  • question_answer
    The power radiated by a black body is P and it radiates maximum energy at wavelength, \[{{\lambda }_{0}}\]. If the temperature of the black body is now changed so that it radiates maximum energy at wavelength\[\frac{3}{4}{{\lambda }_{0}}\], the power radiated by it becomes\[\text{nP}\]. The value of n is [NEET - 2018]

    A)  \[\frac{256}{81}\]                 

    B)  \[\frac{4}{3}\]

    C)  \[\frac{3}{4}\]                                   

    D)  \[\frac{81}{256}\]

    Correct Answer: A

    Solution :

    We know, \[{{\lambda }_{\text{max}}}\text{T=}\]constant (Wien's law) So, \[{{\lambda }_{\text{ma}{{\text{x}}_{\text{1}}}}}{{\text{T}}_{\text{1}}}\text{=}{{\lambda }_{\text{ma}{{\text{x}}_{\text{2}}}}}{{\text{T}}_{\text{2}}}\] \[\Rightarrow {{\lambda }_{0}}T=\frac{3{{\lambda }_{0}}}{4}T'\] \[\Rightarrow T'=\frac{4}{3}T\] So, \[\frac{{{P}_{2}}}{{{P}_{1}}}={{\left( \frac{T'}{T} \right)}^{4}}={{\left( \frac{4}{3} \right)}^{4}}=\frac{256}{81}\]


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