Question

the peak wavelength of radiation emitted by earth is ______.
a earth doesnt emit any radiation
b longer than that emitted by the sun
c shorter than that emitted by the sun
d about the same as the sun, except when sunspots are occurring

Explanation:

Earth emits infrared (long - wavelength) radiation, while the sun emits shorter - wavelength (visible, ultraviolet) radiation. By Wien's displacement law ($\lambda_{max}T = b$, where $b$ is a constant), Earth's temperature ($\sim288$ K) is much lower than the sun's ($\sim5778$ K), so Earth's peak wavelength is longer. Option A is wrong as Earth emits radiation. Option C is wrong (Earth's wavelength is longer). Option D is wrong as their temperatures differ greatly, so wavelengths differ.

Answer:

B. Longer than that emitted by the sun