# Net Power Transfer by Radiation

1. Jun 15, 2011

### ethanabaker1

1. The problem statement, all variables and given/known data

A person with a skin temperature of 33 C and an emissivity of .9 is in a room at 24 C. What is the net power transfer by radiation. Let the area of the body be 1.8 m2.

2. Relevant equations
I=$\frac{P}{A}$
$\Delta$Irad=$\epsilon$$\sigma$T4 (Stefan-Boltzman Law)

3. The attempt at a solution
Temperature difference is 33-24=9 C
(3.34x10-4)(1.8)=6.03x10-4

2. Jun 15, 2011

### SteamKing

Staff Emeritus
It probably would be nice to show a few more units in your calculations.

3. Jun 15, 2011

### ethanabaker1

Well, power should have units of Watts. Emissivity has no units, and I know the Boltzman constant is Wm-2K-4, so I wasn't sure if that means I should convert the temperature difference to Kelvin or not. I left it because both Kelvin and Celsius should have the same temperature difference. But I don't even know if that solution is reasonable.