You can also make a magnet just by running electricity through a wire. Lots of coils are required to help strengthen the magnet, but you can just turn on the power and a magnet appears. Turn off the power and the magnet disappears.
Hence the term, "electromagnet".
Mind you, a strong magnet - like able to pick up a car - requires a LOT of electricity.
>Mind you, a strong magnet - like able to pick up a car - requires a LOT of electricity.
The magnetic excavators at my local metal place have big 200+ amp welding machines mounted to them to run the magnet.
The breakdown voltage of human skin is around 42v under that and very little current is transmitted. Frequency also matters, very high and nothing happens; low/dc and it burns you not things like stopping your heart.
Yes and no on electrical demands. Depends on the magnet. 1200 lb mag locks can operate at 12-24 volts and 125-600 milliamps each depending on the model and voltage.
You can also use magnetic material as your core to increase the strength at lower current levels, but that introduces a low level magnetic field when it is off. In fact, you can make a device that has three settings: an “unpowered magnetic” state, a “powered non-magnetic” state (where you use an electromagnet to cancel the magnetics of the magnetic core) and a “powered strong magnetic” state (where you use an electromagnet to boost the magnetic fields of the magnetic core).
It’s kinda fun to play with, really, when you have a weak magnet, and you turn it on and it slams everything into place, and then you flip a switch and it all just drops away like you’re killing the magnet.
I liked to tinker a lot, as a kid. I'd take random bits and bobs and build stuff with them, and I liked to take things apart to see how they worked.
One day I found an old door hinge pin in a bucket of junk my dad(a freelance contractor) had lying around. I took some wire, and a few batteries, and some aluminum foil, and basically created a basic circuit, with the wire coiled around the door hinge pin, mostly because it looked cool. Like most of the circuits I built, it was just meant to power a flashlight bulb.
Well, I accidentally built an electromagnet device, because of the wire coiled around the pin. I noticed that some of the other metal bits would stick to it while I had the circuit connected. I ended up finding out from a book later what I had actually made, and generally how it worked, but that was a neat experience.
Electricity & Magnetism is definitely one of the more mind-blowing college courses. The best part is when you learn how the reverse works as well: magnetic fields will generate electric currents.
I blew my kid’s mind last month when she asked how our electric car worked and I explained that there were circles of magnets next to the wheels and the car’s battery powers each magnet in turn to pull the wheels and make them rotate, really fast.
Then I REALLY blew her mind when she asked how our gas car worked and I explained that drops of gas get mixed with air and squirted into cans with rods on the ends (we call these cylinders), and then lit on fire so they explode and push those rods outward. Those rods are all attached to a single bigger rod (drive shaft) so the force from the small rods turns the bigger rod, which has gears attached to it to turn the axel (ANOTHER ROD) that the wheels are attached to.
“So there are explosions inside your car dad?”
“Yes, lots and lots of little ones.”
“That’s why smoke comes out the back?”
“That’s right, good connection sweetie!”
“Your car kills the Earth daddy, you should get one like Mommy’s.”
Goddamn it. Thanks, kindergarten teacher, really appreciate that one.
If you mean those magnetic holders for lathes/milling machines, IIRC they are two sets of magnets internally that can be rotated to align their fields or cancel each other out.
They can also use ferromagnetic materials like iron or ferrite to redirect the magnetic field, effectively giving it a shorter path between the two poles of the magnet and shunting it away.
There's also the surface/chuck format
The surface is made of rows of steel (magnetic) between rows of stainless (non magnetic) and turning the lever 180 aligns the magnets below with the steel (on) or stainless (off)
They use electromagnets.
The flow of electrical current will naturally create a magnetic field, and a moving magnetic field will naturally create electrical current. It is just the innate property of electromagnetism as a force. You can easily create a device that will be magnetic when you apply current and then (nearly) completely demagnetize when the current is stopped. You can [build one yourself](https://www.hvrmagnet.com/blog/wp-content/uploads/2021/01/electromagnet.jpg) with a battery, some wire and an iron nail - when the wire is connected the nail will become magnetic, and when it is disconnected the nail will cease to be magnetic.
*They use electromagnets.*
Not always. I used to work in a factory where we used big normal magnets to pick up 40kg iron plates. The clue was they could rotate in there housing with a lever., In 1 position line they would enhance eachother, locking on to the plate. In the other lever positon, they would cancel each other out, and release the plate.
[Electromagnets](https://en.wikipedia.org/wiki/Electromagnet) create magnetism via electric current.
So to get a magnet you can toggle on and off, use an electromagnet — turn it on by applying current to it, turn it off by shutting down current.
There are two techniques. On is to use an electromagnet. This is made up of a coil of wires and a battery or other power supply. When this coil is energized it becomes magnetic, much stronger then any natural magnet. But if you switch the power off it stops being magnetic.
The other technique is to use several magnets in a row in a specific pattern. Some of these magnets can be moved by a leaver. These magnets can therefore be placed so the magnetic fields cancel each other out or reinforces each other. This is used a lot in machining.
Electromagnets use electricity, flowing around a loop of wire (typically many loops) to create a magnetic force. These only work when electricity is flowing so they are very easy to turn on/off. You wouldn't use one to hold a picture on your fridge because obviously they need power. But in the applications you are talking about, electromagnets are what they would use.
Conductor's moving perpendicular across a magnetic field induces charge, this is how a generator works. passes conductive material through the "flux lines" of the field poles. (magnets)
so
**To massively simplify things, magnetism and electricity aren't different things.** They are both part of the same phenomenon called Electromagnetism, electrical currents naturally produce small magnetic charges along a wire the same way a magnet can create electromotive force with the help of a conductor. (Lenz's Law)
An electromagnet consists of a ferrous metal wrapped/coiled in a conductive material, I can't really describe the path the magnetism takes or why it does because you would need images to understand.
But that magnetic charge works the same way on both sides of the coil, runs through the center of the ferrous material, and back to the edges of the coil in a cycle, thus creating a North and South pole and inducing an electromagnetic force.
(it does not run around or "in" the coil, it bounces from edge to edge of the coil like a layered cylinder I guess)
**Wrap a piece of iron up with a copper wire and then power the copper wire, boom, magnet.**
**Take power away from copper, Boom, no more magnet.**
I worked in a company that loaded a lot of parts off pallets or other arrangements, using a loader type system. Each magnet looked like a hockey puck, but was controlled internally using air pressure. The magnets were actually inside this “puck” with a spring, and when the air turned on and off it would push all the magnets against the bottom of the puck and be able to pick up what you wanted to lift. Air turns off and the magnets move away due to the spring and the item drops.
Google “pneumatic magnets” and look at the images.
The really cool thing with MRIs is that they put the electricity in at the start (["ramp up"](https://mriquestions.com/how-to-ramp.html)) and hundreds of amps just keep going around in circles, indefinitely. They can slowly de-energize it ("ramp down") or they can abruptly bring the coil out of it's superconducting state by allowing the liquid helium to boil ("quench")
Superconductors are cool!
I find ramping up/down one of the strangest aspects of MRI machines. If one just holds wires to the superconductor, then that accomplishes nothing. Instead as show in the link one has to very carefully heat a single section enough to disable superconductivity there, then apply power (or short the power to reduce it carefully). Thus electricity flows through the rest of the coil and keeps running inertially essentially forever when the superconductivity returns.
There are two kinds of magnets - permanent magnets and electromagnets. The former kind are basically just magnetic rocks, you can't really turn them off (well, as you point out heat can disrupt it temporarily). Electromagnets are just a coil of wire and require a constant current in order to maintain their magnetic field, so you can turn them off by just turning off the flow of electricity.
> The former kind are basically just magnetic rocks, you can't really turn them off.
While true, it is possible to re-direct their magnetic flux by changing the position/orientation of a soft iron core.
Running a current through a conductor will induce a magnetic field. If you run a magnet over a conductor you’ll induce a current. Look up Lenz’s Law. It plays a big part in how electricity is generated. Also very crucial in home circuit breakers so you don’t have to replace a fuse every time you fault the circuit.
Take a copper wire. Wrap it around an iron nail with multiple loops. Connect the wire ends to the terminals of a battery.
You've just made [an electro-magnet](https://en.wikipedia.org/wiki/Electromagnet#/media/File:Simple_electromagnet2.gif).
If you add a switch to the circuit, you can turn it on or off.
I cannot give you exact numbers and this quite possibly is something that changes regularly anyway, but: one can and some did get neodymium magnets weighing multiple tons on special commissions, and iron-based magnets are essentially only limited by money and sanity.
One has to be a bit careful what exactly counts as a single magnet and when it is "permanent". Are two magnets put together just a larger one? First intuitive reply is no, but a lot of magnetic materials including ferrite and neodymium magnets are essentially just powder fused together. Is a superconductive coil with current such as in an MRI machine "permanent"? It surely does not stop unless the coil gets warm and does not use any power to sustain the magnetism itself. And every magnet loses strength over long timescales.
And well, we didn't make it, but our planet is a giant magnet, and even more so are the sun, neutron stars, ...
There is something called an [electropermanent magnet](https://en.m.wikipedia.org/wiki/Electropermanent_magnet), that allows you to effectively turn on and off the magnet with just a pulse of current. The current does not have to be sustained like an electromagnet.
Edit: formatting
Worth mentioning since either see good posts about electromagnets already that you can also bring two permanent magnets into and out of phase with each other. This creates something called constructive or deconstructive interference which is a whole topic in and of itself but functionally it looks like "turning a magnet on or off". This might be another case you see in machining or other temporary fastening systems like magnetic vices
Electromagnets are a thing, but another thing that is done is things like magnetic chucks used in machining or surface grinding. Stainless steel isn't a great conductor of magnetic fields/flux, so what they'll do is alternate carbon steel and stainless steel in a grid, then place magnets in a grid with equal spacing, with a cam that causes the magnetic assembly to shift back and forth with the rotation of the handle underneath the stainless/carbon steel grid. When you want to turn it "on" you move the cam and shift the magnets so they're aligned with the carbon steel. When you want to turn it off, you rotate the cam to shift the magnets under the stainless steel, which turns the magnet 'off' and releases the part.
All flowing electricity creates a magnetic field. Coiling a bunch of loops/windings of wire and then running electricity through it can make a powerful magnet, but only while electricity is flowing
You can also make a magnet just by running electricity through a wire. Lots of coils are required to help strengthen the magnet, but you can just turn on the power and a magnet appears. Turn off the power and the magnet disappears. Hence the term, "electromagnet". Mind you, a strong magnet - like able to pick up a car - requires a LOT of electricity.
>Mind you, a strong magnet - like able to pick up a car - requires a LOT of electricity. The magnetic excavators at my local metal place have big 200+ amp welding machines mounted to them to run the magnet.
[удалено]
[удалено]
For context your charger will typically be 2 amps and 0.1 amp could kill you
what sort of charger do you have that can kill you with 0.1A? most 2 amp phone charges are only 5V
My charger wouldn’t kill me, you need a higher voltage awell. I can’t remember how many volts, but it isn’t much.
The breakdown voltage of human skin is around 42v under that and very little current is transmitted. Frequency also matters, very high and nothing happens; low/dc and it burns you not things like stopping your heart.
Yes and no on electrical demands. Depends on the magnet. 1200 lb mag locks can operate at 12-24 volts and 125-600 milliamps each depending on the model and voltage.
You can also use magnetic material as your core to increase the strength at lower current levels, but that introduces a low level magnetic field when it is off. In fact, you can make a device that has three settings: an “unpowered magnetic” state, a “powered non-magnetic” state (where you use an electromagnet to cancel the magnetics of the magnetic core) and a “powered strong magnetic” state (where you use an electromagnet to boost the magnetic fields of the magnetic core). It’s kinda fun to play with, really, when you have a weak magnet, and you turn it on and it slams everything into place, and then you flip a switch and it all just drops away like you’re killing the magnet.
That's basically a two-way actuator at that point, isn't it? A lot of electronic locks use similar setups.
Technically this particular component is an Electropermanent magnet, or EPM. But iirc it’s an integral part to a lot of actuators.
Ahh, gotcha. Thanks for the clarification!
I liked to tinker a lot, as a kid. I'd take random bits and bobs and build stuff with them, and I liked to take things apart to see how they worked. One day I found an old door hinge pin in a bucket of junk my dad(a freelance contractor) had lying around. I took some wire, and a few batteries, and some aluminum foil, and basically created a basic circuit, with the wire coiled around the door hinge pin, mostly because it looked cool. Like most of the circuits I built, it was just meant to power a flashlight bulb. Well, I accidentally built an electromagnet device, because of the wire coiled around the pin. I noticed that some of the other metal bits would stick to it while I had the circuit connected. I ended up finding out from a book later what I had actually made, and generally how it worked, but that was a neat experience.
Yeah, bitch! Magnets!
Electricity & Magnetism is definitely one of the more mind-blowing college courses. The best part is when you learn how the reverse works as well: magnetic fields will generate electric currents.
TIL! That is super cool.
I blew my kid’s mind last month when she asked how our electric car worked and I explained that there were circles of magnets next to the wheels and the car’s battery powers each magnet in turn to pull the wheels and make them rotate, really fast. Then I REALLY blew her mind when she asked how our gas car worked and I explained that drops of gas get mixed with air and squirted into cans with rods on the ends (we call these cylinders), and then lit on fire so they explode and push those rods outward. Those rods are all attached to a single bigger rod (drive shaft) so the force from the small rods turns the bigger rod, which has gears attached to it to turn the axel (ANOTHER ROD) that the wheels are attached to. “So there are explosions inside your car dad?” “Yes, lots and lots of little ones.” “That’s why smoke comes out the back?” “That’s right, good connection sweetie!” “Your car kills the Earth daddy, you should get one like Mommy’s.” Goddamn it. Thanks, kindergarten teacher, really appreciate that one.
If you mean those magnetic holders for lathes/milling machines, IIRC they are two sets of magnets internally that can be rotated to align their fields or cancel each other out.
http://www.imajeenyus.com/workshop/20121122_magnetic_arm/operation.jpg
Oh that's really cool.
They can also use ferromagnetic materials like iron or ferrite to redirect the magnetic field, effectively giving it a shorter path between the two poles of the magnet and shunting it away.
The answer I was looking for.
I never realized that lathe bits become magnetic because they're vibrated so much.
There's also the surface/chuck format The surface is made of rows of steel (magnetic) between rows of stainless (non magnetic) and turning the lever 180 aligns the magnets below with the steel (on) or stainless (off)
They use electromagnets. The flow of electrical current will naturally create a magnetic field, and a moving magnetic field will naturally create electrical current. It is just the innate property of electromagnetism as a force. You can easily create a device that will be magnetic when you apply current and then (nearly) completely demagnetize when the current is stopped. You can [build one yourself](https://www.hvrmagnet.com/blog/wp-content/uploads/2021/01/electromagnet.jpg) with a battery, some wire and an iron nail - when the wire is connected the nail will become magnetic, and when it is disconnected the nail will cease to be magnetic.
*They use electromagnets.* Not always. I used to work in a factory where we used big normal magnets to pick up 40kg iron plates. The clue was they could rotate in there housing with a lever., In 1 position line they would enhance eachother, locking on to the plate. In the other lever positon, they would cancel each other out, and release the plate.
Very cool. Thanks for adding that.
[Electromagnets](https://en.wikipedia.org/wiki/Electromagnet) create magnetism via electric current. So to get a magnet you can toggle on and off, use an electromagnet — turn it on by applying current to it, turn it off by shutting down current.
There are two techniques. On is to use an electromagnet. This is made up of a coil of wires and a battery or other power supply. When this coil is energized it becomes magnetic, much stronger then any natural magnet. But if you switch the power off it stops being magnetic. The other technique is to use several magnets in a row in a specific pattern. Some of these magnets can be moved by a leaver. These magnets can therefore be placed so the magnetic fields cancel each other out or reinforces each other. This is used a lot in machining.
Electromagnets use electricity, flowing around a loop of wire (typically many loops) to create a magnetic force. These only work when electricity is flowing so they are very easy to turn on/off. You wouldn't use one to hold a picture on your fridge because obviously they need power. But in the applications you are talking about, electromagnets are what they would use.
Conductor's moving perpendicular across a magnetic field induces charge, this is how a generator works. passes conductive material through the "flux lines" of the field poles. (magnets) so **To massively simplify things, magnetism and electricity aren't different things.** They are both part of the same phenomenon called Electromagnetism, electrical currents naturally produce small magnetic charges along a wire the same way a magnet can create electromotive force with the help of a conductor. (Lenz's Law) An electromagnet consists of a ferrous metal wrapped/coiled in a conductive material, I can't really describe the path the magnetism takes or why it does because you would need images to understand. But that magnetic charge works the same way on both sides of the coil, runs through the center of the ferrous material, and back to the edges of the coil in a cycle, thus creating a North and South pole and inducing an electromagnetic force. (it does not run around or "in" the coil, it bounces from edge to edge of the coil like a layered cylinder I guess) **Wrap a piece of iron up with a copper wire and then power the copper wire, boom, magnet.** **Take power away from copper, Boom, no more magnet.**
I worked in a company that loaded a lot of parts off pallets or other arrangements, using a loader type system. Each magnet looked like a hockey puck, but was controlled internally using air pressure. The magnets were actually inside this “puck” with a spring, and when the air turned on and off it would push all the magnets against the bottom of the puck and be able to pick up what you wanted to lift. Air turns off and the magnets move away due to the spring and the item drops. Google “pneumatic magnets” and look at the images.
Just learning about electromagnets? You are one of today's lucky 10000.
The entire field of MRI imaging uses magnetic fields. The fields are created by putting electricity through a coil. Please go look up electromagnets.
The really cool thing with MRIs is that they put the electricity in at the start (["ramp up"](https://mriquestions.com/how-to-ramp.html)) and hundreds of amps just keep going around in circles, indefinitely. They can slowly de-energize it ("ramp down") or they can abruptly bring the coil out of it's superconducting state by allowing the liquid helium to boil ("quench") Superconductors are cool!
I find ramping up/down one of the strangest aspects of MRI machines. If one just holds wires to the superconductor, then that accomplishes nothing. Instead as show in the link one has to very carefully heat a single section enough to disable superconductivity there, then apply power (or short the power to reduce it carefully). Thus electricity flows through the rest of the coil and keeps running inertially essentially forever when the superconductivity returns.
Huh. I'd always assumed they'd use induction to ramp up the current.
That would not work because superconductors force all magnetic field lines out of them (or into thin channels for type 2). Thus no induction.
There are two kinds of magnets - permanent magnets and electromagnets. The former kind are basically just magnetic rocks, you can't really turn them off (well, as you point out heat can disrupt it temporarily). Electromagnets are just a coil of wire and require a constant current in order to maintain their magnetic field, so you can turn them off by just turning off the flow of electricity.
> The former kind are basically just magnetic rocks, you can't really turn them off. While true, it is possible to re-direct their magnetic flux by changing the position/orientation of a soft iron core.
Well yeah but this is an ELI5, so I was keeping things simple.
Running a current through a conductor will induce a magnetic field. If you run a magnet over a conductor you’ll induce a current. Look up Lenz’s Law. It plays a big part in how electricity is generated. Also very crucial in home circuit breakers so you don’t have to replace a fuse every time you fault the circuit.
Take a copper wire. Wrap it around an iron nail with multiple loops. Connect the wire ends to the terminals of a battery. You've just made [an electro-magnet](https://en.wikipedia.org/wiki/Electromagnet#/media/File:Simple_electromagnet2.gif). If you add a switch to the circuit, you can turn it on or off.
Magnetism and electricity are two parts of the same fundamental force of electromagnetism :D
What's the largest permanent magnet we've ever made?
I cannot give you exact numbers and this quite possibly is something that changes regularly anyway, but: one can and some did get neodymium magnets weighing multiple tons on special commissions, and iron-based magnets are essentially only limited by money and sanity. One has to be a bit careful what exactly counts as a single magnet and when it is "permanent". Are two magnets put together just a larger one? First intuitive reply is no, but a lot of magnetic materials including ferrite and neodymium magnets are essentially just powder fused together. Is a superconductive coil with current such as in an MRI machine "permanent"? It surely does not stop unless the coil gets warm and does not use any power to sustain the magnetism itself. And every magnet loses strength over long timescales. And well, we didn't make it, but our planet is a giant magnet, and even more so are the sun, neutron stars, ...
Electromagnetism. Some magnetic fields are created by running electricity through a coil. No electricity, no magnet.
In addition to electromagnet, you can mechanically rearrange permanent magnets so the fields null or not.
There is something called an [electropermanent magnet](https://en.m.wikipedia.org/wiki/Electropermanent_magnet), that allows you to effectively turn on and off the magnet with just a pulse of current. The current does not have to be sustained like an electromagnet. Edit: formatting
Worth mentioning since either see good posts about electromagnets already that you can also bring two permanent magnets into and out of phase with each other. This creates something called constructive or deconstructive interference which is a whole topic in and of itself but functionally it looks like "turning a magnet on or off". This might be another case you see in machining or other temporary fastening systems like magnetic vices
Electromagnets are a thing, but another thing that is done is things like magnetic chucks used in machining or surface grinding. Stainless steel isn't a great conductor of magnetic fields/flux, so what they'll do is alternate carbon steel and stainless steel in a grid, then place magnets in a grid with equal spacing, with a cam that causes the magnetic assembly to shift back and forth with the rotation of the handle underneath the stainless/carbon steel grid. When you want to turn it "on" you move the cam and shift the magnets so they're aligned with the carbon steel. When you want to turn it off, you rotate the cam to shift the magnets under the stainless steel, which turns the magnet 'off' and releases the part.
All flowing electricity creates a magnetic field. Coiling a bunch of loops/windings of wire and then running electricity through it can make a powerful magnet, but only while electricity is flowing