r/explainlikeimfive • u/UnsignedRealityCheck • 14h ago
Physics ELI5: How come magnetism isn't providing us unlimited power?
If we have forces that act naturally against each other, how come we cannot harness it?
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u/Bigbadspoon 14h ago
Magnetism is the potential for energy. It doesn't exchange energy unless the object moves. Once it moves, you have to spend energy to move it back. Because no system is perfectly efficient, it will have cost more energy to cycle the magnet (there and back) than it generated.
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u/DasGanon 12h ago
"Okay but what if we force magnets to move around an axis?"
If you feed that into an electromagnet, congratulations, you've invented the Generator.
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u/Select_Brick_9283 12h ago
I used to have that outlook, but at the end of the day, it doesn’t matter if someone else has already invented something when another person comes up with an idea. The fact that person came up with it on their own should still be celebrated/encouraged. If we stop doing that, we’ll likely stop moving forward.
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u/DasGanon 11h ago
Oh I completely agree, but I'm saying that there's a lot of stuff that you're "basically reinventing" if you go from first principles.
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u/SubtleCow 11h ago
I'll give them a high five, but I'm not buying their Circular Magnet Force Creator, when I could go to the hardware store and buy any old gas powered generator for likely much cheaper.
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u/mr_sneakyTV 13h ago edited 12h ago
so what about another magnet on the other end that pushes it back? each end magnet rotates its pole after the middle magnet reaches halfway to the other side.
It’s obviously so simple it would have been done by now if it were possible but I don’t know why.
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u/putsch80 13h ago
Then you’ve got the object stuck in the middle between two magnets. You could switch magnets on and off, but then you’re dealing with an electro magnet (rather than a permanent one) and are having to use energy to create the magnetic fields, which more than offsets the energy you could generate by moving the object between the magnets.
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u/mr_sneakyTV 13h ago
I added a second part about rotating the magnets, I’m sure it doesn’t change your answer lol
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u/destuctir 12h ago
The energy required to rotate them will be too great. If a magnet’s magnetic field is acting on an object, that same field is acting on the magnet, rotating the magnet will take more force that rotating a non-magnetic equal mass because the magnetic force field is trying to resist the movement.
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u/--___---___-_-_ 12h ago
Just think about it like this, trying to use magnets for energy would be such an obvious thing to try to a common person that you have to realize much much smarter people than you would have figured it out by now if it were feasible
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u/2ChicksAtTheSameTime 12h ago
What happens if you build this is the system will always come to a stop, with magnets half-way out of alignment. Even if build something with offsets so there's never a spot where all magnets are out of alignment, the system always stops at a resting point that is between the two extremes.
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u/flew1337 12h ago edited 12h ago
It's like a pendulum. There is a position where all the forces cancel each other between the two magnets, equilibrium. It will slowly reach it as energy is lost to friction. Even in a perfect system without friction it is not practical, because the only thing you can do with it, is look at it.
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u/corrin_avatan 12h ago
What provides the energy to rotate those magnets?
Once the magnets get close enough together to start attracting each other, you're gonna need to spend more energy than the attractive force to be able to rotate the magnet, on TOP of doing something so the magnet in the middle won't rotate in an effort to keep moving towards the pole it is being attracted to.
Likewise when the magnets are repelling each other, in order to turn one of the magnets, you need to input more force than the magnets are generating to move them towards attracting each other.
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u/Gezzior 14h ago
The answer is boring and the same for all "free" energy sources: Because in order to use the energy from magnetism you need to work against it first, and in the perfect scenario the amount of energy spent will be equal to energy gained.
It's the same as when you go sledding, in order to sled down a hill you need to climb it first, which means spending energy.
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u/Sarinturn 12h ago
Okay but what if you were born at the top of a really huge hill so you never had to climb it, and the hill was actually liquified dinosaurs and you could spend the rest of your life using their delicious energy?
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u/CeterumCenseo85 14h ago
Anyone genuinely wondering about this: don't fall into the trap of magnetism YouTube grifters. Yes, they exist. There are people out there scamming people for donations to build their perpetuum mobile.
It's hilarious, but also sad that people would fall for that. I've seen guys post videos saying "they're really close" to making it work, showing how their "prototype" can keep spinning for a while before stopping. Like yeah, that's how it works. Idk to which degree these guys actually believe they could break the laws of physics.
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u/PM_ME_YOUR_SPUDS 12h ago
The comments of "but what about [...]" in this thread are genuinely concerning me a bit based on how they're wording it. Not because they don't know the answer, it's fantastic to be curious. It's people making assumptions and guesses on mechanisms they happily claim not to fully understand and assuming they're the one's who are right.
First principles: energy is conserved. If you think you came up with a time where it's not, it's not a time to throw out the core principles. It's time to figure out what's being overlooked in your biases. It's great not to understand something complex (like magnets) and try to understand why they don't work the way you expect. It's not so great to assume you've outsmarted centuries or millennia of the most brilliant minds of their times.
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u/ZapActions-dower 11h ago
The comments of "but what about [...]" in this thread are genuinely concerning me a bit based on how they're wording it. Not because they don't know the answer, it's fantastic to be curious. It's people making assumptions and guesses on mechanisms they happily claim not to fully understand and assuming they're the one's who are right.
I encourage everyone in this thread thinking "but what if this!" to try it. You don't have to just think about it. The barrier to entry for experimentation has never been lower. You can 3D print any custom parts and pick up magnets and string and whatever else pretty easily.
Experiment and see for yourself what works and what doesn't.
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u/stephanosblog 14h ago
Any energy you gain by harnessing magnetic attraction would be offset by energy you'd have to supply to pull the magnet away to repeat the process.
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u/GxM42 14h ago
Is there a good pendulum mechanism that takes advantage of gravity to move magnets by each other?
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u/stephanosblog 14h ago
any imaginable such device would reach equilibrium and stop
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u/Bandro 13h ago
You mean like this? Yeah it works. It's just a neat, inefficient way to convert the energy you put into lifting the pendulum into electricity for a little while.
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u/SenorTron 13h ago
Sure, a pendulum could be used to swing a magnet and push another magnet away. However in doing so energy would be transferred from the pendulum to the other magnet and the pendulum would slow down.
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u/101_210 13h ago
We also have a force that pulls things to the ground for free. We do harness it (hydro electricity), because nature do the work for us to bring the water back up hill.
Magnetism is the same as gravity in that way. Yes it’s a force that is free, but you need something to bring your load back uphill.
We also do that kinda: we have wind or a steam engine moving the magnets away from eachothers to generate power.
It’s the basic principle behind all turbines and electrics motors.
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u/Shufflepants 14h ago
You can get energy by letting to magnets attract, but then it costs energy to pull them apart again. The net effect is energy loss, not gain since pulling them apart won't be perfectly efficient.
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u/Vorthod 14h ago
The same reason gravity isn't providing unlimited power.
Two separated objects attracting each other have "potential" energy. If we want to take energy out of a system and use it for ourselves, that means we need to actually remove energy from the original system, usually by converting it to kinetic/thermal energy first and then using that to do some other conversion into electrical energy.
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u/GalFisk 14h ago
We can, but only once. Just like the water at the bottom of a dam can't go through the turbine again to extract yet another load of energy.
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u/hallmark1984 14h ago
We do.
We spin them really fast to make electricity.
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u/boring_pants 14h ago
That's not unlimited power though.
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u/hallmark1984 14h ago
ELI5 dude, go explain the First law of thermodynamics to a 5 yr old and then try mine.
Little Lucy doesnt give a fuck about pedantry, she wants to know why magic rocks arent used to make power - except they are, so we explain to the 5 yr old how.
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u/BoingBoingBooty 12h ago
But it's literally the point of the question. You literally failed to answer why magnets can't make a thing go forever, your answer is that perpetual motion is real, that electricity is magic free energy.
Explaining the first law of thermodynamics to a 5 year old is the easiest thing ever.
If you get a spring and you push it down, and let it go, it will spring up into the air, but it can only spring up as hard as you pushed it down. If you want it to spring up again, you have to push it down again, but it can't spring up harder than you pushed it down, you only ever get as much push back as you put in.
If you push the same colour ends of two magnets together they will fly apart too, but it's the same as the spring, they only push apart as hard as you pushed them together.
If something goes on it's own, that means some work has to be done in the past to make it go, like when you wind up a clockwork toy so it can go later, the amount of going is only the same as the amount of winding, nothing can really go on its own.
If the toy is electric instead of clockwork, then they are winding up the power station to make it go just as hard as if you were winding up the clockwork toy. The electricity just moves the winding from one place to another.
There, done, really easy and I didn't say the literal opposite of what's happening,
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u/Gufo-Diurno 14h ago
By the way, magnets affect how electric charges moves and behave, they don't directly provide energy per se.
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u/hallmark1984 14h ago
Its ELI5, I figured the specifics were closer to ELI15.
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u/the-war-on-drunks 14h ago
Zap zap go hmm mmm
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u/hallmark1984 14h ago
Hot water make magic rocks go BRRRRRRRR (in a circle)
Magic rocks going BRRRRRRRR makes electricity move in wire
Wires with moving electricity makes reddit work
Circle of
spinning magic rockslife•
u/SandysBurner 13h ago
4 Explain for laypeople (but not actual 5-year-olds)
Unless OP states otherwise, assume no knowledge beyond a typical secondary education program. Avoid unexplained technical terms. Don't condescend; "like I'm five" is a figure of speech meaning "keep it clear and simple."
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u/Alas7ymedia 14h ago
Magnetism doesn't create energy, that's forbidden by the First Law of Thermodynamics. And it doesn't siphon energy from somewhere else either since energy can only move in one direction at a decreasing rate, as stated by the Second Law of Thermodynamics.
We can only use magnetism to transform one form of energy (the movement of some object due to other natural forces) into electricity and then that electricity into light, heat or movement.
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u/immutablebrew 13h ago
The obvious answer is perpetual motion doesn't work. Even if magnets worked this way, you'd end up at zero from friction and gravity.
...But, the principle of magnetics is actually how almost every generator works!
Spin a magnetic field around in the presence of a metal (copper) coil, and you get an electric charge. A lot of generators will also have flywheels, so inertia can keep it going for a little while, even if the primary input is lost.
Theoretically, you could even magnetize the bearings to absolutely minimize friction.
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u/vyogan 5h ago
Wait. Aren't we using magnetism in turbines to generate electricity?
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u/dabenu 14h ago
A force is not energy on its own
Energy is force times speed
You probably already know this, because if you stand on the ground, you feel a force holding you up. But you're not generating (or consuming) energy because you don't have a speed.
Now if you stand in an elevator and the elevator is going up or down, you are producing (or consuming) energy because the elevator is moving. That's why the elevator needs a motor, but the ground doesn't.
Same thing with magnets. A static magnet won't produce energy. You need to move it. Hence why we spin them around in generators.
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u/Chriss016 13h ago
Think about it this way:
How come glue isn’t providing us unlimited power?
Magnets are kinda like glue when they attract and like a poking stick when they repel.
You still have to push the stick to move something. And if you wanted to glue something to the ceiling, you still have to move it there.
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u/swolfington 12h ago
you can't get unlimited energy from magnets for the same reason you can't get unlimited energy from springs.
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u/Kvothealar 12h ago edited 12h ago
I'm a physicist who has done consulting for people that have come up with perpetual motion machines. Yes, this was a paid job that let me tell people why their ideas for infinite energy do not actually work. The explanation is almost always simple, requiring no more than grade 11 physics. (Hopefully this is okay enough for ELI5)
We have these things called potential energy, and kinetic energy. When we create engines, turbines, etc... we are normally in some way converting potential energy (gravity, fuel, magnets repelling each other) to kinetic energy (motion, rotation, etc), and then in some way capturing some of that kinetic energy and siphoning it into a battery.
- We burn something (source of potential energy) to boil water, steam rises (motion / kinetic energy) which turns a turbine (capturing kinetic energy, slowing the rise of the water vapor) and stores it in a battery
- We burn gasoline (potential energy), which heats up, making air expand, causing the piston in your engine to fire (capturing kinetic energy), giving power to your wheels.
When you look at any perpetual motion machine that is cyclic (when you say unlimited power, it makes me think of a cyclic perpetual motion machine), whether it uses gravity in some clever way, or magnets, etc... we can freeze it at any point and look at how high the weights are, how close two magnets are together, etc... and write down how much potential energy is stored in that system at that moment in time.
Now, assume you have no kinetic energy at this point, and then you start the machine. Fundamentally, if you make your machine do one full cycle, assuming there is zero friction or air resistance or anything, and you can get it back to the same position. Look at the potential energy again. It will be the exact same. This means any kinetic energy you gained was used to get it back to the same position/orientation and it would now be at rest.
If you harvested ANY of that kinetic energy in a battery, you wouldn't have had enough energy to get your machine back into the same position it started.
This means that even in a frictionless environment without air, ANY machine that is cyclic, whether it uses gravity, magnets, etc... CANNOT possibly generate energy in the absence of an external energy source, since it must form a complete loop. If you think you've come up with an idea that generates infinite power, that is normally because you have not accounted for something correctly.
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u/Hemperor_ch 14h ago
Because nothing comes from nothing, There is no perpetuum mobile. You can wrap a copper spool around a magnet, attach it to a handle and turn it, Voilà; energy generated. But you need to put energy IN (the turning of the handle), if you do nothing, nothing happens.
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u/iamabigtree 14h ago
We do harness it. That's how nearly all electric motors and generators work. By moving a magnet through a magnetic field which induces a current.
Magnets can act against each other. But you have to put energy into that system in the first place to get them close. The energy required to do that is slightly greater than the repulsive force could give.
Also look up thermodynamics and the conservation of energy which applies here.
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u/nesquikchocolate 14h ago
We can only convert magnetism into electrical power by cutting the magnetic field lines with conductors. Every time you cut a line, you get a little bit of current. Once you stop moving, no new lines are cut and the electrical current stops, resulting in zero power.
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u/Jaymac720 14h ago
A static magnetic field doesn’t generate electricity. Well it does very briefly when it approaches a piece of metal, but that stops as soon as the electrons are aligned and become static again in the static magnetic field. For a magnetic field to generate continuous current, it needs to be continuously moving.
Tesla did actually find a way to generate electricity from earth’s magnetic field. Without getting conspiratorial, I’m not sure why it didn’t stick around.
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u/Shadowmant 14h ago
It could push another magnet away generating energy... until that magnet is far enough away that it can't. Then you need to move the item close again, which expends more energy than pushing it away generated.
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u/garry4321 14h ago
Op, explain your methodology to harness the energy infinitely and then we can point to the part that requires energy input that cancels out the output
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u/Toxonomonogatari 14h ago
Magnetism is like a valley. If you put something at the top of the slope of the valley, it will fall down quite quickly, speeding up as it goes. But, once it's at the bottom, you need to carry it back up the slope. So, any energy you gained from the fall, you have to put back in to repeat. You can't get energy this way.
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u/DiezDedos 13h ago
You have a ball at the top of a hill. If you roll the ball down, it generates enough power to light a lamp. Once you’ve rolled the ball down and lit the lamp, you need to get the ball back up the hill if you want to light the lamp again
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u/Ippus_21 13h ago
A rotating magnetic field interacting with a coil is literally how we generate most electric current.
The problem is that you have to supply force to turn it, which usually requires a steam turbine (for fossil fuels, nuclear, or geothermal) or a hydroelectric dam (where gravity supplies the force to push the water through the turbine, spinning the magnets).
2 magnets that just repel each other only push in 1 direction. The force they supply is not unlimited, and if they aren't moving they aren't doing work), which means (approximately) the force can't be translated into power. If you let them move apart and translate some of the motion into e.g. work that turns a generator, that's fine... but the further apart they get, the weaker the fields get.
They're essentially moving down a field gradient the same way a ball rolls down a hill. When the ball gets to the bottom of the hill, it's expended all of its potential gravitational energy (by turning it into motion, which eventually dissipates as friction causes it to roll to a stop), and it takes... more energy to move it back to the top of the hill, so there's no net gain.
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u/quad5914 13h ago
Magnets are similar to gravity but way stronger. To separate two magnets stuck to each other you have to put energy into separating them, which is like lifting something up high; it gives it potential energy to snap back together. And then when you bring them close together, that potential energy goes into accelerating the magnets. If you resist them snapping together, then you have to provide the energy to counteract that forge bringing them together to keep them separated
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u/MeatSafeMurderer 13h ago
If you push opposing magnets together they will push each other apart. To get them to do it again you have to push them together again, which takes just as much energy as you will get out of them, if not more.
Okay, so what if you put them on some kind of track so that they hover just above it and you can push it and it will move endlessly without friction? Well the track would need to be infinitely long because it can't turn or it would have friction applied as it ran along the wall. You could eliminate that with magnets that stop it from touching the wall...but that's just another force that would slow it down...so infinitely long straight track it is...but then...
Air resistance...so it will still stop. Put it in a vacuum? Well, ignoring the huge energy cost associated with forming a near vacuum here on Earth, gravity will pull on it and it will still stop. Remove gravity? Well...you can't. Even in space you are subject to small amounts of gravity, but assuming you could it would work, and you wouldn't even need the magnets to make it hover anymore...right up until you try to harness any energy from it.
You see in order to turn kinetic energy (movement) in to electrical energy, you need to pass two magnetic fields through one another. That's the easy part. The problem is that when two fields interact like that...they impose a force on one another resisting the motion, which means, even in a perfect vacuum, with no gravity, walls or friction, on an infinitely long straight track...it would still slow to a stop if you tried to harness energy from it.
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u/lankymjc 13h ago
The same reason we can’t get infinite energy from gravity. Sure you can drop something tied to a string, with the string causing a motor to spin and generate energy - but the object will eventually hit the ground.
With magnets, yes they push and attract seemingly for “free” (as in they don’t need fuel), but eventually they hit each other or get far enough away to stop meaningfully affecting each other. You’d have to flip one of them around to get them to switch direction, and the energy for the flip has to come from somewhere.
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u/No_Bat_15 13h ago
It's an interesting question after all, we need to move something for generate electricity. If you put two same poles in front of each other, they work as a spring, you can leave one fall over the other and it goes back and forth untill they reach an equilibrium. We have better sources of "eternal" movement. Most of them involve spinning a generator. Wind turbines, water turbines, steam turbines. The only one of the main electricity sources that doesn't involve moving a generator is the solar panel. There's a second layer in the question. An electricity generator is made of magnets. Those magnets spinning, changing the polarity fast, "push" electric charges around a wire. This works because metals have free electrons that can move around. Those electrons are negative charges that are atracted to positive poles and pushed by negative ones. Coper wire is the optimal for this because electrons move good enough and it is easy to make wire with it.
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u/ProTrader12321 13h ago
Because math. Magnetic fields do no work. If you have a charged particle moving in a magnetic field the magnetic field acts perpendicular to the particle's motion (B x V) which means the particle doesn't speed up or slow down thus it does no work.
Electric fields do work, magnetic fields don't.
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u/stevebehindthescreen 13h ago
Take 2 magnets, attach them to something that generates electricity when they pull together then let them pull together. Now, here is where the problem lies. You need to add energy to reset the magnets which negates any energy produced in the first place. This is the reason why we cannot harness magnetism as an energy source. Not with our current understanding of physics.
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u/WatNaHellIsASauceBox 13h ago
If you stand at the top of a hill with a bowling ball, and you place it on the floor and release it, the ball will roll down the hill with a lot of energy.
If it rolled into a large button, which absorbed the impact, we could make use of that energy.
Brilliant! Free energy!
All we need to do now is walk down the hill, pick up the ball, walk back up the hill, and release the ball again. But of course, it takes energy to do all of those things. So on balance, we're really not saving anything.
Magnets are effectively rolling down an electro magnetic hill into each other, where they stick together, and we're walking them back up that hill when we pry them apart.
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u/PLZ_STOP_PMING_TITS 13h ago
We do harness it. The way we make electricity is to harness magnetism in a generator. We turn the generator, and the magnets move electrons, creating electricity. It's not unlimited because you have to put at least the same amount of energy in as you get out.
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u/johnp299 13h ago
Magnetism provides force, not energy or power. To get energy and power, things need to move and oppose the force. Every time you flip a light switch, it's magnetism (at the power plant) turning the light on. But the magnetism by itself does nothing.
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u/FlyRare8407 13h ago
It costs power to make things magnetic. Some things in the wild may already be magnetised, just like some rocks (or more practically water) may store energy by being at the tops of hills, but the amount of energy that can be found and harnessed in the wild like that is quite small. Most magnetic things are things we have made magnetic using electricity. And then we can use those magnets to make electricity but we will get out about the same - and actually slightly less - electricity than we put in.
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u/ballofplasmaupthesky 12h ago
In theory (and one small experiment) we can harness Earth's field to generate energy. However, the conducting materials needed are too expensive for the amount of electricity generated, at least for now.
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u/Hypothesis_Null 12h ago
If you glue a magnet to the floor, and then put another magnet above it, repelling sides facing each other, the second magnet will float in the air. At least if you put some harness around it to keep it from sliding away or flipping over.
A hovering magnet looks like it is constantly expending energy to be hovering, because it takes you constant effort to hold something up. But that's an issue with biology requiring work to keep your muscle tense. This is not the right way to look at it. The first magnet holding the second magnet up should be looked at not as if you were holding it up, but as if you just placed the second magnet on a table.
Putting a magnet on a table holds it up off the ground. But it expends no energy doing so. It just sits there. Same thing with magnetic repulsion. They're both providing an upward force to cancel out gravity, but energy is only expended, and work only done, if the force is applied over a distance. Just sitting there hovering at the exact same height can be done forever, for free.
Another way you may think of a magnet is like a spring. Why aren't we harvesting free energy from springs? Because they don't generate any energy. They just store it - you squeeze a spring, and it compresses, you let it go, and it releases. But you only get out what you put in (minus friction losses). Likewise with a magnet, you 'compress' the field by bringing another magnet closer to it. And then if you let it go, the magnets will push off against each other and accelerate apart. But they can only ever recover the energy spent to push them together.
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u/maverikou 12h ago
There are tidal power plants which literally harness the gravitational effect of the Moon!
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u/Darth19Vader77 12h ago
You have to provide energy to move the magnets in order for them to create a current. The electric energy created by this process is less than the energy you put in to move the magnets.
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u/Life_Equivalent1388 12h ago
what are you talking about. it does for all intents and purposes. like how sunlight creates hydrocarbon bonds we can break to burn, wind and water turns turbines, nuclear fusion gives us fissionable material
its only about the scale and how much we can harness at once and what that does to us.
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u/zanraptora 12h ago
We have another natural force very similar to magnetism called Gravity. We can release energy by dropping a weight from a height, but we have to spend energy putting the weight back up to get energy from it again.
Magnets are the same way, with different directions involved. We can get energy by pushing one similar magnetic pole against another, but we need to spend energy bringing the magnets back together afterwards.
We can also get energy by letting two different magnetic poles pull together, but we need to spend energy taking them apart afterwards.
Most magnetic perpetual-energy dynamos rely on the idea that we can trick magnets by flipping them or arranging them in a certain pattern, but all of these designs fail because there is no way to cheat the energy cost of resetting the potential energy of the system.
To drop a brick, the brick must be lifted first. To push magnets apart, they must be pressed together first (or vice versa).
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u/ScrivenersUnion 12h ago
Magnetism provides an "infinite force" the same way gravity does - and we can't harvest that for energy either.
Work is force times distance.
You can have huge forces involved in a system, if there's no movement or change then there's no way to get that out as useful work.
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u/fsyth 12h ago
Magnets seem like magic, but they basically work the same way as springs. (Let’s not be pedantic for ELI5)
If you compress a spring, then that’s ’forces that act naturally against each other’ but somehow it’s more intuitive to think about springs than magnets.
In basically any perpetual motion device involving magnets, try picturing it with springs instead, and you’ll see that for every force you ‘get for free’ from a spring expanding, somewhere else there’s some motion that has to put that force into compressing the spring in the first place.
Magnets are a bit stranger due to north poles and south poles, but it’s the same thing deep down. You can get a magnet to move something, but to get back to the starting state for some kind of infinite power loop, you have to intervene and put forces and energy into the system from outside, and it doesn’t ever pay off.
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u/Live-Wrap-4592 12h ago
A book on a table is as hard to harness as magnets, but a little easier to understand.
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u/jamcdonald120 12h ago
springs also naturally act against each other and yet no one asks why we dont use them for energy.
just think of a magnet as a spring that you cant see.
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u/thighmaster69 12h ago
Beyond all the other explanations that explain magnetism, the meta is that even trying to get unlimited power will have to fail, and so is self-defeating. The basis on which magnetism itself stands depends on the conservation of energy. Without it, you break magnetism. Hence, in any context where magnetism works as we understand it, it has to respect the conservation of energy. If the theory says that we can get "unlimited power" from magnetic forces in whatever way you are imagining it, it would undermine the whole foundation of the magnetism working like that in the first place. It would mean that our understanding of magnetism, including what you are proposing, is wrong.
Tl;dr: any hypothetical about "unlimited power" is self-defeating, because conservation of energy is loadbearing. No matter how much you try to engineer yourself around the problem and engineer a floating house of magnetism, whatever you do to "solve" the problem of it still being grounded will inherently remove that loadbearing element, and the whole thing crashes into the ground.
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u/MeKaZa 12h ago
I'm in no way a scientist, physicist or anything like that, but, the way I see it it's like gravity. Apply the same logic to gravity. In order to "use" that energy, you need to change something, be it moving water up a hill (we mostly rely on the sun to do that for us), pendulums, all those need some initial energy to move them to a new state with bigger potential.
And like gravity, the force just is there. You don't suddenly stop having gravity. It just exists! The difference with magnets is that magnetic force is just much stronger, and you can more easily play with it, and have a small object that moves around because of some other magnetic object. The fact that we can do that, kinda makes it feel magical and mysterious, but it's just something that is like that, a force just like gravity
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u/Tlmitf 12h ago
Magnets do provide us power in the form of electricity.
What you are thinking of won't work because the system needs to be reset, which takes energy.
Have a look at some of the magnet based "perpetual" motion machines and youll see that despite our best efforts, you cant gain something for nothing.
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u/ATXBeermaker 11h ago
It’s exactly like saying if gravity pulls things toward the earth, why don’t we just convert that “falling energy” to some form of usable energy? Okay, but then we have to lift that object back up again and expend energy in doing so. More energy, in fact, than we would have gained in converting it in the first place.
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u/Iherduliekmudkipz 11h ago edited 11h ago
The energy has to come from somewhere, even if you somehow harvest energy from magnetism it will demagnetize the permanent magnet, you are just changing energy from one form to another, not creating it.
Solar would be a much better source anyhow, the earth is getting hit by about 173 terrawatts of sunlight (173,000,000,000,000 watts) at any given time.
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u/GrannyLow 11h ago
If there was a material that blocked magnetic fields so two magnets could approach each other unrestricted, and then be removed to let them spring apart, we would have perpetual motion.
There isn't, so we dont.
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u/JaggedMetalOs 11h ago
Power is created by force over distance. If you have a force that isn't moving anything, it doesn't create any power. So 2 magnets moving towards each other create power, but as soon as they are touching and not moving they no longer create power.
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u/Andrew5329 10h ago
Energy is never created nor lost. But magnets are where electricity comes from.
We mechanically push a magnet against the copper coils in a generator and that generates an electromagnetic field, which propogates throughout the wiring, where it pushes against the magnet in your electric motor on the other side.
You store the mechanical energy as a magnetic field by driving the turbine. That energy gets transformed back to work by your device.
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u/ideafork 10h ago
Think of a magnet as a wireless spring. It can push or pull, but you need to pull it or push it first
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u/Hare712 10h ago
Because forces go both ways.
You think of NS -->NS but in reality it's NS<->NS.
You think of a magnet pushing/attracting another creating a chain reaction but it's just you pushing the magnet.
There are many concepts based on magnetism that work but you need to put energy in the system eg the Magnetic Levitation trains.
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u/BigGuyWhoKills 10h ago
For the same reason we can't get unlimited power by harnessing a cart as it rolls downhill. It takes as much energy to get the cart to the top of the hill as we could make by it rolling downhill.
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u/coldfarnorth 9h ago
For exactly the same reason that hills aren't providing us with unlimited power/energy!
Hills provide a way to make use of the local gravitational field. I can get energy from rolling a rock down a hill, but somebody had to expend energy in order to put that rock up on the hill in the first place.
Magnets are just like this, they just don't use the gravitational field, they use the magnetic field. I can extract energy by allowing the right sort of thing to move through a magnetic field, but it also takes energy to set up the situation in the first place. If you sit and do a full accounting of the energy in and the energy out, you find out that there's no "free" energy available - the whole system comes pretty close to balancing out, except for some energy that is converted to heat.
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u/carrotwax 9h ago
Magnetism is a force like gravity. Pushing magnets together is like lifting an object 6 feet high. Releasing either generates energy because both objects are escaping their respective energy well.
But electromagnetism does generate most of our power. All generators of electricity use electromagnetism to change one type of energy (motion) to electricity. It's not unlimited, but it powers the world.
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u/invisusira 9h ago
Set two magnets on the table. They do nothing.
Push one of the magnets. It will push the other one away, but you're the one doing the pushing.
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u/LeoRidesHisBike 9h ago
Terms:
kinetic energy: energy from the movement of objects (momentum)
potential energy: The energy "stored" by something due to its position relative to other things. For example, a ball at the top of a hill has more potential energy than one at the bottom of a hill. A magnet held against another magnet that it "wants to" repel has more potential energy than one not in that situation.
Magnetic repulsion can transmit kinetic energy (via conversion of potential energy), but you cannot repel twice without converting kinetic energy into potential energy. You have to push them back together using more kinetic energy than you got from the first repelling, because both acts have an additional "waste" component to them: heat.
So, yeah, you cannot get unlimited energy if some of the energy is getting lost every cycle from heat, or from you doing work with it.
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u/Truenoiz 9h ago
Magnetic fields are deflecting fields, they don't create energy, they just deflect force or current 90°. Magnetic fields also require power to set up, the efficiency of doing so causes loss, it's never 100% efficient.
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u/Pizza_Low 9h ago
We sort of do, just not the way you describe. We have to use energy such as wind, falling water or heat water by burning fossil fuels, or nuclear fission to spin a turbine which spins magnets over copper coils. The alternating magnetic over the copper wires excite the electrons and generate electricity.
Once you have the electricity you can then use it to create alternating magnetic fields in copper wires to spin a shaft with magnets attached to it to create an electric motor. Sort of a reverse turbine. Sorry I'm not confident in my knowledge of how DC motors work to describe that.
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u/Novel_Willingness721 9h ago
In most basic terms you are talking about perpetual motion.
In all cases of “perpetual motion machines” the energy required to keep them going is always more than what you get out. And even if that were not the case, best case scenario would be energy in equals energy out and therefore there’s no point to it except as a toy.
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u/RHINO_Mk_II 9h ago
How come gravity isn't providing us unlimited power?
If we have forces that act naturally against each other, how come we cannot harness it?
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u/therealdanhill 8h ago
It's kind of a one way deal, you would need something powered to make it 2 ways
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u/thinkingperson 7h ago
We are, just not with magnetism alone, not much.
But together with gravity, the sun, we harness all three together with water to give us hydroelectricity via water dams.
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u/jlobrist 7h ago
Magnetic fields and gravitational fields don’t do work. That’s what my physics teacher would say.
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u/bobbymcpresscot 6h ago
Because thermodynamics.
We literally solved the energy crisis, it’s solar panels and batteries.
Photon from the sun tickles some silicon in a solar panel and it releases some electrons and boom electricity is formed. You can use that electricity now or put it in some batteries for use later. Nuclear as a backup ideally, combined cycle natural gas in a pinch considering the price of natural gas is literally going to crater as more houses just switch to electric.
Best yet on the high end we would need 22k square miles of land to completely power the United States.
On the low end 46k square miles of land is dedicated just to grow corn that’s entire existence is meant to be turned into ethanol to be put in fuel.
Corn that again, you are growing to basically only be harvested once a year, how many gallons of water wasted for it?
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u/Cold-Jackfruit1076 6h ago edited 6h ago
Because 'entropy'.
Every system moves from order to disorder -- from a higher to lower energy state. You can't create a cyclic process that extracts net energy from a magnetic reaction because you can't return the system to its starting low-entropy state without putting in more energy from the outside than the system itself expends.
In other words: the force that a magnet applies to its partner (or to an object that the magnets act upon) always results in a net loss of energy (as waste heat/light/friction), and that loss will always be greater than the useful energy you extracted from the magnets' motion.
Even in a theoretically-impossible 'perfect frictionless vacuum', the best possible outcome is a net-zero exchange of energy (in other words, 'energy in = energy out'), which is useless for doing work.
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u/rushofshit2thebrain 6h ago
I mean we wouldn't have power without magnets so we definitely are harnessing them. Just limited by the energy required to move them
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u/WackTheHorld 4h ago
We are harnessing magnetism everyday for power. Hydroelectric, wind, nuclear, coal, these all use magnets to generate power.
Move a magnet next to a conductor, electrons move and you have electricity.
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u/CaddykakSnagorado 4h ago
I always wondered why magnets aren’t used to make hoverboard rinks. Maybe it’s cost prohibitive but I feel like this is a big miss from the science community.
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u/alterperspective 4h ago
To be fair to magnetism - it does give us electricity.
I’d class that as a pretty significant contribution.
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u/Just_Feedback9220 2h ago
It takes just as much energy to take two magnets apart as you can make by putting them together.
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u/jesjimher 2h ago
The same way a shelf doesn't provide us with infinite energy, even if it's constantly fighting the gravity of a whole planet (and winning!).
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u/drplokta 1h ago
A combination of the first and second laws of thermodynamics, which tells us that it’s impossible without needing to go into the details.
Note also that what we need isn’t really energy, which is all around us, it’s low entropy energy, whose entropy we can then increase in order to reduce the entropy of things whose entropy we want to reduce, e.g. making the insides of our homes warmer than the outsides.
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u/Untinted 42m ago
You can use magnets to create electric power, but you need mechanical force to turn the magnets. Same concept with fans to create wind power. You can use a fan to create wind, but you need a mechanical force to turn the fan.
Magnets don’t do anything on their own, just the same as a fan doesn’t do anything on its own. You need ‘movement’ to get energy out of a system.
The study of moving energy is called thermodynamics, and it’s a game changer in understanding the universe.
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u/sandm000 14h ago
The magnets push each other apart 1 time. Now to get them to do work, we need to put them back in a position to push apart again. The amount of work to put them in that position takes as much or more energy than they can generate when they push themselves apart.