![]() ![]() Max Planck was able to explain the spectrum in 1900, but he had to resort to a desperate mathematical trick, assigning a characteristic energy to the light-emitting material that depended on the frequency of the light. ![]() As I mentioned when writing about Einstein's truly radical contribution to physics, the most obvious approach to this problem produces disastrous results. This spectrum turns out to be surprisingly difficult to explain, though. You can see an example of this shape in this famous xkcd cartoon. The color of the light does not depend strongly on the properties of the material being heated, just its temperature, and the spectrum of light- the intensity of the light emitted at various wavelengths- takes the form of a broad peak whose wavelength changes location in a fairly simple way. The light emitted by a hot object is called "blackbody radiation," and has some interestingly simple properties. He is a Fellow of Royal Society Te Apārangi, which means he’s one of the top experts in his field of engineering.Max Planck in 1901 (photo from Wikimedia) next to n incandescent bulb and its spectrum. Our expertĭistinguished Professor Geoff Chase from the University of Canterbury answered this question. When heated, these special gases glow and create light. Because it is so very thin, it heats up really fast, so when we flick the switch the light comes on! More modern light bulbs replace the filament with a gas. ![]() The metal used to make the filament glows when it becomes hot, and thus we have light. The electricity being run through it causes it to heat up (this is another reason we coat electric cables in rubber). A filament is a very, very thin wire, and if you look closely at a light bulb like this you can see these wires. The second common thing is that electricity can be used to heat things up – think of how warm your computer gets when you use it a lot and you hear the fan whirring to cool it off, or the charger for your parent’s laptop or phone might get warm when it is plugged in. ![]() First, they require electricity, which is the first step. Ok, there are lots of types of light bulbs! However, they all have two basic things in common. ![]()
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