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Measuring non-ionizing radiation

by Great Smoky
Tags: measuring, nonionizing, radiation
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Great Smoky
#1
Apr19-12, 07:21 AM
P: 8
Does everything give off some sort of radiation? Example: water, oil, mud, etc. If so, how can it be measured?

Is there a way to translate a radio wave into a frequency in the visible spectrum and see it bounce off a wall?
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sophiecentaur
#2
Apr19-12, 01:23 PM
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Everything does give off electromagnetic radiation BUT it is also absorbing EM at the same time. Most of the EM radiation to which we are subject, most of the time, is due to the temperature of our surroundings. A 'hot body' will cool down in colder surroundings. If it's in a vacuum, then all the energy enters and leaves a body by radiation. Once a body is at the same temperature as its surroundings, the power absorbed is the same as the power it radiates.
One answer to your second question involves realising that EM waves of different wavelengths have photons of different energies. Light has photons with high energy. Radio waves have photons of low energy. (X ray photons have higher energy still). It is often possible to 'translate' energy from high energy to low energy. For instance, a beam of light can warm up a small block of metal so it will radiate Infra red - and all frequencies down to DC. The other way doesn't work, on its own, so well.
If you were to take a concentrated beam of microwaves, you could heat up an object enough to make it glow visibly. But the object would be radiating the whole spectrum of EM, corresponding to a 'hot body'. You wouldn't just get light off it. To do that, you'd need some much smarter apparatus involving detectors and amplifiers if all you wanted was light off the wall.


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