Question

The intensity of radiation emitted by the sun has its maximum value at a wavelength of $510\text{nm}$ and that emitted by the North Star has the maximum value at $350\text{nm}$. If these stars behave like blackbodies, then the ratio of the surface temperatures of the sun and North Star is

• A. $1.46$
• B. $0.69$
• C. $1.21$
• D. $0.83$

Answer 1

The correct option is B $0.69$

From Wein's displacement Law,
${\lambda }_{m}T=\text{constant(b)}$
$T=\frac{b}{{\lambda }_m}$
$\frac{T_{sun}}{T_{northstar}}=\frac{({\lambda }_m{)}_{northstar}}{({\lambda }_m{)}_{sun}}=\frac{350}{510}\approx 0.69$