A black body is at a temperature of 2800 K. The energy of radiation emitted by this object with wavelength between 499 nm and 500 nm is ${\text{U}}_{\text{1}}$, between 999 nm and 1000 nm is ${\text{U}}_{\text{2}}$ and between 1499 nm and 1500 nm is ${\text{U}}_{\text{3}}$. The Wien’s constant $2.88\times {10}^{6}nm$K. Then :