Question

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

• A. $14\mu m$
• B. $70\mu m$
• C. $2.8\mu m$
• D. $28\mu m$

Answer 1

The correct option is C $2.8\mu m$

Applying Wien's displacement law, $\lambda T$=constant
where, $\lambda$ =wavelength of maximum energy, T=absolute temperature
Let ${\lambda }_1$ be required wavelength at 1000K
$\Rightarrow {\lambda }_1\times 1000=14\times 200\Rightarrow {\lambda }_1=2.8\mu m$