(a) If the human body acts like a blackbody, use Wien’s displacement law (see problem 45) to calculate the body’s wavelength of maximum emission. Assume an average skin temperature of 34°C.
(b) In what part of the electromagnetic spectrum is the light?

(a) 9439.8 nm

(b) infrared

Explanation:

Temperature, T = 34°C = 307 K

(a)

According to the Wein's displacement law

where, b is the Wein's constant.

b = 2.898 x 10^-3 metre kelvin

λm x 307 = 2.898 x 10^-3

λm = 9.44 x 10^-6 m = 9439.8 nm

(b) it lies in infrared radiation.

it is given that trillions of microbes make up to 1% to 3% of the body mass.

let's take average of this percentage: 2%

consider the average mass of the human body as 70 kg.

then, trillions of microbes would have mass  

therefore, 100 trillion micro-organisms would weigh:

this is an approximate value and could change depending on the mass of the human body and percentage of the microbes present in it.

average mass per microorganism =