Answer:
[tex]1.07\cdot 10^{-3} m[/tex]
Explanation:
The peak wavelength of the spectral distribution can be found by using Wien's displacement law:
[tex]\lambda=\frac{b}{T}[/tex]
where
[tex]b=2.898\cdot 10^{-3} m\cdot K[/tex] is Wien's displacement constant
T is the absolute temperature
For the cosmic background radiation, the temperature is
T = 2.7 K
So, the corresponding peak wavelength is
[tex]\lambda=\frac{2.898\cdot 10^{-3} m\cdot K}{2.7 K}=1.07\cdot 10^{-3} m[/tex]