good/bad absorbers
and
good/bad emitters
2007-02-21 21:44:49 · 9 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Let us take radiating / absorbing heat as radiating / absorbing Infra Red Radiation.
Anything else would make the question impossible to answer. After all, what is heat?.
The best surfaces to radiate and absorb heat are non-reflective surfaces (Infra Red Radiation is on the edge of the spectrum of light).
The worst surfaces to radiate and absorb heat are reflective surfaces, for the same reason as given above.
Matt black colour = good absorber and emitter.
Shiny silver colour = bad absorber and emitter.
Looking at the bigger picture, heat landing on a good absorber surface can easily be re-emitted. The rate at which the heat landing on the good absorber will be re-emitted will be dependant on its surface temperature. Hence to keep the heat in the object, it is best if the material of the object is a good conductor of heat, so that it immediately conducts the newly received heat radiation throughout its body, rather than allowing the surface temperature to get much higher than the core temperature.
Hence for a good emitter/absorber you are looking for matt black surface colour, and good thermal conductivity.
For bad absorber/emitter you are looking for shiny silver colour, and low thermal conductivity.
2007-02-21 22:16:15 · answer #1 · answered by Valmiki 4 · 0⤊ 0⤋
Good emitters, bad absorbers with large, white surface areas.
2007-02-22 11:31:14 · answer #2 · answered by Norrie 7 · 0⤊ 0⤋
Black Bodies - they absorb all radiation and emit all radiation. i.e. Good Absorber and Good Emitter.
2007-02-22 05:59:44 · answer #3 · answered by Doctor Q 6 · 0⤊ 0⤋
radiation is best absorbed and/or emitted when there is a large surface area and a dark colour.
since a matt surface packs more surface area into the same amount of surface(because it is rough), and black is the darkest colour, so a matt black surface is the best type of surface to absorb and/or emit heat.
2007-02-22 08:08:10 · answer #4 · answered by a fellow human 2 · 0⤊ 0⤋
ok
Good Absorbers, like anything black! eg. a black bin-bag
Bad Absorbers are anything white eg. paper
Good Emitters are things like tin foil
Bad emitters are anything like plastic
2007-02-22 06:09:49 · answer #5 · answered by Fire Juggler 2 · 0⤊ 0⤋
good absorbers of heat and good emitters of heat
2007-02-22 05:48:07 · answer #6 · answered by agius1520 6 · 0⤊ 0⤋
Anything black as opposed to white. Black surfaces hold more heat.
2007-02-22 16:06:17 · answer #7 · answered by CLIVE C 3 · 0⤊ 0⤋
mirrors
2007-02-22 06:08:03 · answer #8 · answered by Anonymous · 0⤊ 0⤋
radiators and cookers :)
2007-02-22 05:51:55 · answer #9 · answered by Vix 3 · 0⤊ 0⤋