Wien's displacement law

Wein's Displacement Law

It states that the product of the wavelength corresponding to which maximum energy is emitted and absolute temperature of black body is always constant i.e.

λm T = b

Where b is called wein's constant. Its value is 0.002898m K in SI.

Wien's law tells that the total energy emitted by perfect black body is not uniformly distributed over the entire wavelength emitted by it. The energy emitted is maximum for a particular wavelength λm. It is common observation that when a body is heated more and more, the colour of body changes from red (loger wavelength) to yellow (smaller wavelength). This observation can be explained on the basis of Wien's law as with increasing temperature, the emission of energy is maximum corresponding to smaller wavelength.