3 ms·
Just for clarity, is that energy measured at the source, or at a certain distance?
by kakarot 8y ago
Just for clarity, is that energy measured at the source, or at a certain distance?
- microcolonel 8y agoI am not a physicist, so I'm probably at least subtly wrong, but... The photon has the same energy regardless of where it is measured, but the total intensity of the radiation (of all the photons reaching a unit of area normal to the source) decreases with the inverse square of the distance because the photons move generally (except insofar as they are acted upon by forces like the gravitational and electromagnetic) in straight lines at diverging angles. https://en.wikipedia.org/wiki/Inverse-square_law https://en.wikipedia.org/wiki/Inverse-square_law
- kakarot 8y agoI'm aware of the inverse square law, which is the entire point of my question. Even measuring a couple feet from the antenna would produce a massive difference in energy levels.
- microcolonel 8y agoMy point was that measuring the energy of a photon is independent from distance. A given photon's energy will remain the same until it interacts with something. The maximum allowed intensity in the ISM band is a known value, 1W; but the energy of the photon is what you should generally be concerned with.
- jdietrich 8y agoThat's the energy carried by each individual photon. In terms of the number of photons, a typical lightbulb emits one two to orders of magnitude more; the number of photons illuminating a surface will reduce with the square of distance (assuming an isotropic radiator). The illuminance in direct sunlight is two or three orders of magnitude greater than in an artificially lit room; sunlight also contains photons at UV wavelengths, which can carry up to two orders of magnitude more energy than visible photons. Sunscreen is opaque at UV wavelengths but effectively transparent at visible wavelengths, partly for aesthetic reasons but mainly because the lower-energy visible photons cause negligible damage to skin. UV photons are sufficiently energetic to break apart bonds in DNA, but visible photons only carry enough energy to heat the skin. Mobile phones are utterly feeble radiators, both in terms of photon energy and the quantity of photons. In terms of your exposure to electromagnetic radiation, they're a rounding error.
- deleted 8y ago[deleted]
- kakarot 8y agoIf it's per-photon, isn't that a useless metric without discussing the amount of photons being pushed out? I'm not worried about non-ionizing radiation. I'm not even worried enough about actual ionizing radiation sometimes. I'm just interested in the details behind the typical phone antenna.
- turbo_fart_box 8y agoYou didn't read all the above replies