3 ms·
If you are facing something really cold and black - like space then the blacker your radiator is the more power you can emit at a given temperature. In theory
by nobody3141592 15y ago
If you are facing something really cold and black - like space then the blacker your radiator is the more power you can emit at a given temperature.
In theory a perfectly reflective silver object would never cool down and a perfectly black one would cool to -270C however much power you dumped into it
- ars 15y agoThat is not true. A perfectly reflective silver object still emits blackbody radiation. And a perfectly blank one will absorb light, heat up and also emit blackbody radiation.
- nobody3141592 15y agoA Mr Kirchof would disagree with you if he wasn't dead. A perfect emitter facing an infinite cold sink is in perfect equibirium at the temperature of the cold sink.
- ars 15y agoOf course - but that's not what you said. You said: "...would cool to -270C however much power you dumped into it" and that is not true. And in any case you don't need to be a perfect emitter to be in equilibrium with the temperature of the cold sink, all you need is infinite time, but any emitter, no matter how bad will eventually equilibrize.