1. Mar 6, 2012

moogull

1. The problem statement, all variables and given/known data
Raising the temperature of 1$cm^{3}$ 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 $m^{3}$ 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
P=IV
Energy of a photon gas = ($\frac{8\pi^{5}*k^4}{15c^3*h^3}$)V$T^{4}$
radiative flux = $\sigma$$T^{4}$ 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?