The Cosmic Background Radiation Permeating the Universe Has the Spectrum $2.7 - \mathrm { K }$

Short Answer

The cosmic background radiation permeating the universe has the spectrum of a $2.7 - \mathrm { K }$ blackbody radiator. What is the peak wavelength of this radiation? The constant in Wien's law is $0.0029 \mathrm {~m} \cdot \mathrm { K }$ .