On 05/10/2020 18:49:59, williamwright wrote:
On 05/10/2020 12:28, JohnP wrote:
A black radiator gives off more heat.

Why should the efficiency of a surface in absorbing light affect its
efficiency in radiating heat?

CH radiators will emit strongly in the long wave IR band:
https://www.giangrandi.ch/optics/bla...ient-large.png

It is possible to have a black surface that is reflective in the
infrared. Your typical black anodised aluminium is a good example.

A thick slice of Alumina is a good example of a material that looks
white (good reflector) in the visible but is a strong emitter / absorber
in the IR.

In very general terms a matt surface will absorb/emit in the infrared.

Most non-metallic surfaces are quite good emitters. Aluminium is a very
good reflactor.