A consequence of Wien's displacement law is that the wavelength at which the intensity per unit wavelength of the radiation produced by a black body has a local maximum or peak, λ λ peak , is a function only of the temperature: λ λ peak = b T , where the constant b, known as Wien's displacement constant, is equal to h c k 1 5 + W 0 ( − − 5 e − − 5 ) ≈ ≈ 2.897 771 955 × 10 m K. W 0 is the Lambert W function. So λ λ peak is approximately 2898 μm/T, with the temperature given in kelvins. At a typical room temperature of 293 K (20 °C), the maximum intensity is at 9.9 μm.