1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Kitchen Oven (Blackbody radiation)

  1. Mar 6, 2012 #1
    1. The problem statement, all variables and given/known data
    Raising the temperature of 1[itex]cm^{3}[/itex] of water (1 gram, water has a heat cap. of 4.2 J/g*K) using energy from a cavity filled with black body radiation. The water is to change from 299K to 300K. The radiation is initially at 450K.
    If the cavity has a volume of 0.1 [itex]m^{3}[/itex] how long would you need to have the heating coils turned on to heat the water? (voltage of coils is 240V, and current is 20A)

    2. Relevant equations
    Energy of a photon gas = ([itex]\frac{8\pi^{5}*k^4}{15c^3*h^3}[/itex])V[itex]T^{4}[/itex]
    radiative flux = [itex]\sigma[/itex][itex]T^{4}[/itex] sigma is stefan-boltzmann constant

    3. The attempt at a solution

    I want to say that the energy input from the coils should be enough and the time would be 4.2J /480V*20A, but that can't be it. Honestly I'm totally lost on this one because the radiative flux would require that you know a surface area, but one is not given (and maybe that the volume doesn't even matter), any thoughts?
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted