Which surfaces are the best emitters of infrared radiation

Or if you wanted to compare the two extremes, you can use just matt black and shiny silver. Place them all the same distance from a radiant heater and turn on the heater. After a known amount of time, e. Record the temperature of each plate. The plate of highest temperature is the best absorber. The best absorber will be the matt black plate, followed by gloss black, followed by white, followed by silver. Click here to go to the next topic. Click here to go to the previous topic.

Click here to go back to the Science menu. Skip to content. Home Notes Co-ordinated Sciences — P6. Recognise radiation as the method of heat transfer that does not require a medium to travel through.

Radiation is the emission of energy. Identify infra-red radiation as the part of the electromagnetic spectrum often involved in heat transfer by radiation. This table summarises some differences:.

You can see that dull surfaces are good absorbers and emitters of infrared radiation. Shiny surfaces are poor absorbers and emitters but they are good reflectors of infrared radiation. If two objects made from the same material have identical volumes, a thin, flat object will radiate heat energy faster than a fat object.

This is one reason why domestic radiators are thin and flat. Black matt surfaces are also very good emitters of infrared radiation once the object has become warm. On the other hand, light shiny surfaces are poor absorbers and poor emitters of infrared radiation. They're also good reflectors. In hot countries, the houses are often painted in white or light colours.

This is to keep the house cool as the white surfaces are poor absorbers and good reflectors of heat radiation. Another example is a shiny teapot. The shiny light surface of the teapot is a poor emitter of infrared and so the teapot stays hot for longer. Sometimes we need objects to lose their heat and remain cool. For example, the cooling fins at the back of a refrigerator.

These are usually painted a black colour with a matt finish, so the fins can emit infrared heat quickly to keep the refridgerator cool. Remember that heat energy will always transfer from a hotter object to a cooler object - never the other way round. Also, a hot object will emit more heat radiation than a similar cooler object. A key point in all of this is that when the teapot has reached the same temperature as the surroundings, it will emit and absorb heat energy at the same rate.

The surface colour and texture would make no difference and the same amount of heat is transferred in both directions.