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Keeping homes warm

Heat transfer by radiation

Heat can be transferred by infrared radiation. Unlike conduction and convection, which need particles, infrared radiation is a type of electromagnetic radiation that involves waves.

Light from the sun reaching earth

Radiation can even work through the vacuum of space. This is why we can still feel the heat of the Sun even though it is 150 million km away from the Earth.

Different surfaces

Some surfaces are better than others at reflecting and absorbing infrared radiation. The table summarises some differences.

differences in surfaces absorbing radiation

surfaceability to reflect infrared radiationability to absorb infrared radiation
dull or roughpoorgood

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. Radiators are often painted with white gloss paint. They would be better at radiating heat if they were painted with black matt paint, but in fact, despite their name, radiators transfer most of their heat to a room by convection.

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