3 ms·
Have you ever tried to pick up seawater with an electromagnet?
by jbay808 5y ago
Have you ever tried to pick up seawater with an electromagnet?
- willis936 5y agoIs it really so trivial? Water is diamagnetic. Salt water is conductive. All I expect is a "yes we thought about it" in the form of measurements of ocean floor salt water magnetic permeability. If the models prove too much they could always drop a magnetometer off a boat.
- jbay808 5y agoI just don't understand why you think this matters. Even if the relative permeability were as high as, say, 2, it would only move the 500 uT effect radius by some tens of centimetres. But just from common sense, it must be several orders of magnitude less than that, because otherwise your compass wouldn't work near the ocean. In practice, you need a very sensitive instrument to even measure the relative permeability of water, which already means that it's completely negligible for the purposes of this discussion. Wikipedia quotes water's permeability as 0.999992. By that measure, an eighty-times stronger argument against the researchers' due diligence would be "how do they know the cable isn't actually carrying 1599 amps? Did they measure the current?"
- monocasa 5y agoConsidering running ADSL over wet string didn't work until the water was salted there's obvious EMF considerations at play. https://www.revk.uk/2017/12/its-official-adsl-works-over-wet-string.html https://www.revk.uk/2017/12/its-official-adsl-works-over-wet...
- jbay808 5y agoI'm pretty sure that's due to saltwater's conductivity, not any EMF considerations. Conductivity will result in some partial cancellation of the AC magnetic field. But not enough to matter at 60 Hz, which is within the Extremely Low Frequency band used for communications with submarines. https://en.wikipedia.org/wiki/Communication_with_submarines https://en.wikipedia.org/wiki/Communication_with_submarines