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NEET-XII-Physics

pp year:2018

with Solutions -
Qstn# 11 Prvs-QstnNext-Qstn
  • #11
    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 nP. The
    value of n is :-
    (1)``\frac{3}{4}``
    (2)``\frac{4}{3}``
    (3)``\frac{256}{81}``
    (4)``\frac{81}{256}``
    digAnsr:   3
    Ans : (3)
    Sol. P = AT4 &implies; P  T4
    According to Wein's law 
    m
    1
    T
    &implies;
     
       
    4
    m
    1
    P &implies;
     
    =    
    1
    2
    4
    m2
    1 m
    P
    P
    &implies;
     
    =  
     
     
    4
    2 0
    1
    0
    P
    3P
    4
    &implies; = &implies; =
    nP 256 256
    n
    P 81 81
    
    
    3
    CODE - PP