Discussion
A body which is radiating energy such as the sun has a wavelength where it has maximum energy emission (λm) that is given by, where T is temperature, P is pressure :
Answer: A
The relation is \(\lambda_{m}T\) = Constant, Wien's displacement law.
For a black body, the wavelength of peak emission is inversely proportional to its absolute temperature:
\[ \lambda_{m} T = b \approx 2898\ \mu\text{m K} \]
The Sun, at about 5800 K, therefore peaks near 0.5 micrometres in visible light, while the Earth, at about 288 K, peaks near 10 micrometres in the infrared. The hotter the body, the shorter its peak wavelength.
Pressure does not appear in the law at all, which rules out both options with P. \(\lambda_{m}/T\) = Constant would make the peak wavelength grow with temperature, the opposite of what is observed.
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