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Wien displacement law theory

Wien displacement law, discovered in 1893, gives a mathematical relation to calculate the spectral brightness of emitted thermal radiations of heated objects at a particular temperature T. To accomplish precise calculations, Wien introduced a fixed numerical quantity in his mathematical formula and named Wien's constant.

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Wien displacement law theory

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  1. Wien displacement law The Wien displacement law is a temperature-specific empirical relation for the peak-intense wavelength of a blackbody curve. Wilhelm Wein, in 1893, derived the Wien displacement formula to measure the highest spectral radiance of a blackbody as a function of its wavelength at a particular temperature. λm x T = b λm = Maximum wavelength of emitted radiation. T= Absolute temperature b = Wien's constant Wien displacement formula It interprets an inversely proportional relationship of maximum intense blackbody radiation wavelength (λm) with its absolute temperature. Wien's constant: 1. 2. Wien displacement law calculation: It is a fixed numerical value. The product of λm with the body's temperature on the Kelvin scale is known as Wien's constant. The numerical value of Wien's constant is 2.89 x 10 ^-3 meter Kelvin. The alphabet "b" symbolizes it. Its SI unit is Meter Kelvin, and the CGS unit is Centimeter Kelvin. Question-1: If λm= 750 nm, then calculate T in the Kelvin. Answer: 3. λm = 750 nm b= 2.89 x 10^-3 mK Wien's law formula is λm x T = b T = 2.89 x 10^-3 mK/750 x 10^-9 m T= 3853 K In this way, we calculate the temperature at various emitted radiation wavelengths and vice versa. 4. 5. Wien displacement law graph: 10,000 The Wien displacement law graph for the peak wavelength positions of hot material at its absolute temperatures shows a linearly declining curve. It unfolded the shift of peak-intense wavelength towards shorter wavelengths at higher temperatures. Hence, the term 'displacement" implies the movement of crest wavelength to shorter wavelengths. 7,500 5,000 2,500 0 350 450 550 650 750 Applications: Limitation: Wien displacement law gives accurate results only for short- range wavelength measurements. It is invalid at longer wavelength radiant emissions at the same temperature conditions. It helps to measure the spectral radiance of emitted thermal radiations by quantifying their absolute temperatures. It plays a principal role in designing thermal equipment for heating and medical treatment purposes. Blog: https://jayamchemistrylearners.blogspot.com/

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