If a wire carrying current produces magnetic field around it, why its not attracted to nearby metals ? In a general household.
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Actually, this is how most medical MRI (magnetic resonance imaging) are possible.
A current of around 450 to 600 amps (depending on the Magnet construction model) keeps running through superconductive coil wires (around 16 km of wires!), which can generate a magnetic field from 0.55 Tesla to even 7 Tesla.
Putting that into perspective, the earth’s magnetic field is around 0.00006 Tesla. Hence, a 3 Tesla MRI scanner is around 60,000 times stronger than the earth’s magnetic field.
Just to add up, this magnetic field is generated “just” to net magnetize the spinning direction of electrons of the human body (99% of the time, the Hydrogen electrons). How the image is actually produced is based on Radio Frequency stimulation of those electrons and FFTs.
It is. But four things: One: The current moving through house wires tends to be small. A couple amps here and there , and occasionally 10-20 amps.
A current of 20A for example will create a magnetic field about as strong as the earths when measured close to the wire. I don’t recall any magnets sticking to the ground haha.
Two: The current reverses 60x a second. Which means the magnetic field also reverses itself 60x a second. So the magnetic field kinda cancels itself out. Imagine it was strong enough to attract metal. It would attract then repel them attract …
Three: this is a circular field. It doesn’t act like a bar magnet. So even if it was not alternating current I’m not sure if a piece of metal would “stick “
Four: there are two current carrying wires in most home wiring . The two wires are very close and they are out of phase with one another so they really do approximately cancel each other’s magnetic fields.
The effect is weak, but it’s just about possible to feel it. There was a bit of a body modification trend many years ago of embedding a tiny neodymium magnet (those really strong ones) under the tip of your finger. The nerves in your finger are sensitive enough [that you can feel the AC current in wires as tiny vibrations](https://www.wired.com/2006/06/a-sixth-sense-for-a-wired-world/).
They are.
In terms of “induced magnetic fields” the current flowing through the wires is very small. But not 0.
It is significant enough to be observed if you come up with a creative test.
But not significant enough to be observed in most conditions.
The inverse square law governs the strength of magnetic fields, and has a lot to do with it.
The magnetic field strength around a current-carrying cable is proportional to the current – this is Ampere’s Law. (It does not depend on the voltage)
Most common household electrics operates at 15 amps or less, and the magnetic field at those currents is too small to have “obvious” effects. Also in most domestic electrics there are usually a pair of wires within the power cord, and as the current flows “out” on one and “back” on the other (equal currents in opposite directions) the external magnetic field cancels out anyway.
The magnetic field close to a single conductor wire carrying a couple of amps is not enough to normally notice, but *is* enough to move a magnetic compass needle – see for example this video:
[https://www.youtube.com/shorts/qwR6527VEEw](https://www.youtube.com/shorts/qwR6527VEEw)
(if you do try this experiment yourself, it is important to only use an *alkaline single-use battery*, probably an *AA*, *C*, or *D* cell – and *only touch the wire for a second or so* at a time. **Never** use any kind of rechargeable battery as you’d risk burning yourself or starting a fire)
In welding applications or seriously high power electrics where currents of 100’s amps are flowing it is not unusual to see a cable physically twitching when the current starts or stops, due to magnetic effects. Another Redditor on this thread has probably posted a video.
[it IS attracted.](https://youtu.be/gZ5zD75yWwM?t=12) it’s just a really really weak attraction. you can either make a coil (a single wire is considered a single loop coil of wire) the more loops, the stronger the magnetic force. or more current. or both.
you can test this yourself. take a small short wire and use it to short out a 9v battery right next to a compass (or the compass app on your phone) and you’ll see the compass move. those are sensitive enough to detect the attraction created by the wire.
EDIT: also, the compass thing won’t work with household wiring because those wires are in pairs that are opposite polarity. magnet polarity (north or south) matches with the electrical polarity, so if you swap positive and negative on the battery, the field your wire makes will be the opposite of what it was. if you have two wires next to each other, with opposite polarities, their fields will cancel each other out
>ELI5: If a wire carrying current produces magnetic field around it, why its not attracted to nearby metals ? In a general household.
It is.
However, a general household uses [Romex-style](https://images.homedepot.ca/productimages/p_1000108206.jpg?product-images=m) wiring. That means that in addition to the wire carrying current in one direction, producing a magnetic field of a certain polarity, there is a second wire carrying current in the opposite direction, producing a magnetic field of the opposite polarity. These two magnetic fields cancel each other out, and the net effect is no magnetic field and no attraction to nearby metals.
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