Register to reply

Thermodynamics question, heat transfer via radiation.

by mrspeedybob
Tags: heat, radiation, thermodynamics, transfer
Share this thread:
Apr13-12, 05:17 AM
P: 696
Suppose I have an object with a surface area of 2 square meters at a temperature which causes it to radiate energy at a rate of 1 kw per square meter. It has a very large thermal mass and so for the purposes of this experiment, a constant temperature . Around this object I have a system of mirrors and lenses which focus all of this energy onto a second object with a surface area of 1 square meter. The mirror and lens apparatus also works in reverse so that all radiation emited by the 1 square meter object ends up striking the 2 square meter object.

I have 2 kw of power striking my 1 square meter object, so it should assume a temperature at which it will radiate 2 kw of power, but that would mean it is radiating 2 kw per square meter which would make it hotter then the first object. That can't be right because they should trend toward the same temperature.

I feel like it should be obvious, but I can't see how the temperatures trend toward equal.
Phys.Org News Partner Physics news on
Vibrational motion of a single molecule measured in real time
Researchers demonstrate ultra low-field nuclear magnetic resonance using Earth's magnetic field
Bubbling down: Discovery suggests surprising uses for common bubbles
Apr13-12, 05:44 AM
P: 22,286
It is the temperature difference between the objects that determines the radiation rate/direction.

Register to reply

Related Discussions
Thermodynamics : Heat transfer question. Introductory Physics Homework 1
Radiation heat transfer Mechanical Engineering 0
Radiation/convection heat transfer problem. (Thermodynamics) Engineering, Comp Sci, & Technology Homework 1
Electromagnetic Radiation and Heat Transfer General Physics 8
Thermodynamics, Heat transfer question Engineering, Comp Sci, & Technology Homework 7