1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Infrared Emission of A Person

  1. Dec 6, 2008 #1
    In order to detect SARS, airport officials would use infrared cameras to find potential carriers. A healthy individual would be detected to emit 100microwatts at 37C body temperature, what would a sick individual at 40C body temperature emit? With this answer, what is the difference in emission of a sick individual and a healthy one?

    2. Relevant equations

    Radiation out = (5.67*10^-8)(e)(A)(T)^4

    Where e ~ 1.

    3. The attempt at a solution

    0.0001W = (5.67*10^-8)(1)(A)(37)^4

    A = 0.000941044249m^2

    X W = (5.67*10^-8)(1)(0.000941044249)(40)^4

    X W = 0.000136594455

    0.000136594455-0.0001 = 0.00003659W = 36.59 microwatts

    However, this is apparently the wrong answer. Am I going at the problem in a completely wrong direction?

    Thanks alot for any help.
  2. jcsd
  3. Dec 6, 2008 #2


    User Avatar
    Homework Helper

    Welcome to PF.

    For one thing the Stephan-Boltzmann equation implies the use of degrees °K not °C.

    So your temps should be 310° and 313°K

    All other things being equal then

    X/100 = (313)4/(310)4

    should yield an answer in microwatts shouldn't it?
  4. Dec 6, 2008 #3
    Wow that was stupid. Thank you very much for the correction..yes that produces a correct answer.
  5. Dec 6, 2008 #4


    User Avatar
    Homework Helper

    Easy to overlook.

    Yet amazingly think how smart nature is to get it right every time.

Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?

Similar Discussions: Infrared Emission of A Person
  1. Infrared radiation (Replies: 6)