Naked Science Forum
Non Life Sciences => Technology => Topic started by: thedoc on 09/04/2013 03:30:01
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ramzi asked the Naked Scientists:
Hi! I was wondering if standing in front of a microwave oven while wearing wireless headphones could interfere with or damage the headphones in any way permanently?
If so, how long would one need to be standing in front of them?
Thanks! :)
What do you think?
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Both operate on a frequency near 2.4GHz some interference is possible it would depend on the bandwidth of the receiver in the headphones and the exact frequencies on which both operate.
the leakage from properly maintained microwave ovens is low so the range of interference should not be too large and there would be no possibility of any damage.
The precise frequency on which microwave ovens operate depends on the dimensions of the magnetron tube and operating voltage both of which will vary as it heats up also the headphone receiver is not a very precise device so it is rather a matter of luck whether or not you get interference.
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Microwave ovens reduce the range of most common WiFi systems, as they generate a broadband noise on the channels in use ( actually over a broad part of the band, and with a 50/60 Hz AM modulation on it as well) that reduces the ability of the receiver to decode the data being sent to it. This results in either no signal, a reduced range or multiple errors on the data, and depending on the application you will have no audio in your bluetooth ( which uses the same band) or noise or blocky audio.
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Some wireless headphones operate in the 900MHz range and are presumably not troubled by microwave ovens.
The 2.4 GHz band is meant as a free for all band for use with devices of low frequency precision like microwave ovens and such devices cannot be blamed for interfering with more precision devices that also make use of this band provided the emitted power is below authorised limits.
http://en.wikipedia.org/wiki/ISM_band
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There are several major causes of induced failures in electronics:
- Radio Frequency Interference: Where devices operating on related frequencies create electrical signals which are strong enough to interfere with the normal operation of the other device (eg microwave ovens reducing the range of a WiFi device). Normal operation resumes as soon as the interfering signal is turned off.
- Dielectric Breakdown: Where the electrical signal induced in a susceptible device is large enough to exceed the breakdown voltage of the device, causing a permanent fault. This will often occur as soon as the susceptible device is exposed to the maximum signal level (eg <1 second). However, you may need to try a few positions to find the maximum signal level. Some devices are more susceptible when switched on, others when switched off.
- Overheating: Where the signal level does not cause permanent failure by itself, but it causes gradual heating of the device, until the temperature gets high enough to cause failure. This could take minutes. However, as long as the power levels are not too high, and the device is not thermally insulated, contact with the air or your ears should be enough to keep it cool.
- Non-Destructive Lockup: Where the interference levels are high enough to cause misreading of digital signals, the operation of the device is put in an invalid state, perhaps because of a computer misreading memory. Normally operation is restored by turning the power off and back on.
- Provided the door seal on your microwave oven is intact, only cause 1 should apply to devices outside the microwave.
- Placing any piece of electronics inside a microwave will immediately destroy it due to causes 2 & 3, as soon as the device rotates out of a null in the microwave radiation.
- Turning on a microwave without some microwave-absorbent object inside (like a piece of food or a cup of water) is likely to cause the microwave to eventually fail due to cause 3.
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In short, you may experience temporary interference (cut-outs or garbled sound) while near the operating microwave, but you shouldn't suffer any permanent damage to the wireless headphones (unless the microwave is seriously damaged/faulty).
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I think that this would only happen if your microwave oven leaked radio waves. :)
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Even when operating normally, microwave ovens can be expected to leak a small amount of microwaves (enough to be detectable with the right equipment, and potentially enough to cause interference to nearby radio devices operating on a similar frequency, 2.45GHz, but not enough to be harmful to humans or to cause permanent damage to other electronic equipment).