Question

Temperature of two stars are in ratio 3 : 2. If wavelength of maximum intensity of first body is $4000\stackrel{\circ }{A}$, what is corresponding wavelength of second body?

• A. $9000\stackrel{\circ }{A}$
• B. $6000\stackrel{\circ }{A}$
• C. $2000\stackrel{\circ }{A}$
• D. $8000\stackrel{\circ }{A}$

Answer 1

Answer: (B)

$6000\stackrel{\circ }{A}$

According to Wien's displacement law
${\lambda }_{m}T=constant$
$\therefore \frac{{\left({\lambda }_m\right)}_1}{{\left({\lambda }_m\right)}_2}=\frac{T_2}{T_1}$
Here, $\frac{T_1}{T_2}=\frac{3}{2},{\left({\lambda }_m\right)}_1=4000\stackrel{\circ }{A}$
$=4000\times {10}^{-10}m$
$\therefore {\left({\lambda }_m\right)}_2=\frac{4000\times {10}^{-10}\times 3}{2}$
$=6000\times {10}^{-10}m$
$=6000\stackrel{\circ }{A}$