Question

A black body at a temperature of $2600 \,K$ has the wavelength corresponding to maximum emission $1200 \,\mathring{A}$. Assuming the moon to be perfectly black body the temperature of the moon, if the wavelength corresponding to maximum emission is $5000 \,\mathring{A}$ is

• A. 7800 K
• B. 6240 K
• C. 5240 K
• D. 3640 K

Answer 1

Answer: (B)

From Wien law
$\lambda_{1} T_{1} =\lambda_{2} T_{2} $
$T_{2} =\frac{\lambda_{1} T_{1}}{\lambda_{2}}$
$=\frac{1200 \times 2600}{5000}$
$T_{2} =6240 \,K$