Question

A black body at $200$ K is found to emit maximum energy at a wavelength of $14$ $\mu$m. When its temperature is raised to $1000$ K, the wavelength at which maximum energy is emitted is :

• A. 14 $\mu$m
• B. 70 $\mu$m
• C. 1.8 $\mu$m
• D. 2.8 $\mu$m

Answer 1

The correct option is D 2.8 $\mu$m

From wien's displacement law,

$\lambda \times T=$ constant.
so
$1000\times \lambda =200\times 14$
$\lambda =\frac{200\times 14}{1000}=2.8\mu m$