Why doesn't my mobile phone pick up the electro-magnetic wave emitted by my water heater? I admit my knowledge of physics is very little, but I did study topics on EM and stuff in school.
I was reading about computer networks and I read about antennas and how they are just wires or strips of metals that have some circuit attached to them. Then it occurred to me that the water heater I use to heat water which is rated 1000v, 1A is also a coiled wire(http://img6a.flixcart.com/image/immersion-rod/g/a/f/immersion-1500-bajaj-400x400-imadmke6xugdcynk.jpeg). So when current passes through this water heater, it should setup a magnetic field spiraling the coils of the water heater. When I bring my mobile near this immersion heater say about 4m or so close to the wire, the magnetic field should setup up a current in the metal of the antenna of my phone right? Which should fry my mobile! But it doesn't!!
I don't remember the exact equations behind induction but hey, even though my phone runs on like 5v DC and I guess 0.1 A battery, it can send data to a device three rooms across!! So how is it that the water heater can't fry my mobile?
 A: The electricity through the coil is probably coming directly from the network, so it oscillates at either 50 or 60 Hz. That would be the frequency your antenna radiates. This is very different to the frequencies your phone works in, around 1 GHz (a thousand million† Hertzs, or twenty million times faster). So, essentially, your wave (weak, as Lemon pointed out), just passes through without even seeing your phone's antenna, it is just too small (from an electromagnetic wave point of view).
This is actually a relief, because we are flooded with electromagnetic waves at 50 Hz and above (a few harmonics: 100, 150, 200... decreasing in intensity). The electric wires inside the walls are also emitting, and by sheer numbers, they are emitting much more than your water heater.
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† Or billion, but not always. So I prefer to keep it explicit.
A: That heating element has 4 turns and looks to be a few cm across. It most likely consists of a copper wire coated in nickel. The relative permeabilities of which are ~1 and ~100, respectively.
It follows that the magnetic field created by your heating element, at its strongest point, will be roughly 1 Gauss (only a few times stronger than the magnetic field of the earth).
