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Chapter 9: Q77E (page 409)

At what wavelength does the human body emit the maximum electromagnetic radiation? Use Wien's law from Exercise 79 and assume a skin temperature of70οF.

Short Answer

Expert verified

The wavelength at which human body emits maximum electromagnetic radiation9480nm .

Step by step solution

01

Wien's displacement law.

From Wien's displacement law:

λpeak=bT …… (1)

Where, whereTis the absolute temperature in kelvins, andbWien's displacement constant equal to2.897×10−3m⋅K

λmax=2.897×10−3m⋅KT

…… (2)

02

The wavelength at which human body emits maximum electromagnetic radiation. 

The temperature of human skin is 70°F=294.26K.

Calculation:

Substitute the numerical value in equation (2)

λmax=2.897×10−3m⋅K294.26K=9.84×10−6m=9840nm

The wavelength at which human body emits maximum electromagnetic radiation9480nm .

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