I couldn't resist photographing this radiant heater. This type of heater was always used as an example in Physics text books. The bright bits are tightly wound coils of thick wire. They must have high resistance because the current heats the wire until it glows at the red end of the spectrum. As well as the visible light, a lot of infra-red must also be released. It is reflected in our direction by the concave silver backing. Silver is a bad absorber of infra-red. These heaters are great because they heat a room most quickly. The infra-red travels at the speed of light. The other issue is that the metal case would conduct electricity in the event of a fault. Thus there is an earth wire soldered onto the case to conduct away stray electric current and blow the fuse. The case can't be made of insulating plastic because it would melt.
