could magnets be used to create a renewable source of energy?

[Good Intentions]

Perpetual means it keeps on going without stopping. So unless you remove all the water from the planet or stop the sun shining then hydro electric is perpetual.

No, it doesn't. Hydroelectricity does not generate perpetual energy. You'd be in a lot better position scientifically if you tightened up your use of terms.

Magnetically charged lodestone has been lying around on the planet for millenia and comes for free.

So does oil. Does burning oil count as perpetual energy?

You can make a permanent magnet by stroking a magnet along a piece of iron so "ridiculous" amounts of energy aren't required.

It's not permanent. Look up the power-usages of useful electromagnets and you'll see what I mean.

 

[Crispy]

Just as much 'work' is done if the two bars are touching against each other, supporting each other. Magnetism just allows action at a distance, which seems freaky - but is completely natural. After all, if the two bars support each other by touvhing, they're not actually touching - their respective molecules are repelling each other electrostatically. If you zoomed right in, you see that the atoms are actually 'floating' relative miles away from each other - and there's no energy being used up to make them do so either.

 

[WouldBe]

Work is not being done, gravitational force is merely in equilibrium with magnetic force.

Things do not defy gravity without some form of energy being put in. In a tug-of-war the rope may not be moving but 'work' is definately still being done.

...but since the planet will run out of water, and the sun will stop shining, it's not perpetual, is it?

By that point in time I don't think we will care anymore as most life will cease to exist well before all the water disapears.

...but you can't get any energy out of your "free" magnets except by doing work on them (i.e. moving them about).

What protects us from ionising radiation from space? Oh yeah it's free energy from the earths magnetic field.

 

[5T3R30TYP3]

I am reading a book that this thread reminds me of. Xes, you should read this book if you are interested in 'free energy' and 'perpetual motion machines' and that sort of thing.

 

[WouldBe]

No, it doesn't. Hydroelectricity does not generate perpetual energy. You'd be in a lot better position scientifically if you tightened up your use of terms.

Depends how you define perpetual.

So does oil. Does burning oil count as perpetual energy?

Of course not because oil is limited and you have to expend energy getting it out of the ground and into the power station.

It's not permanent. Look up the power-usages of useful electromagnets and you'll see what I mean.

Is a compass not 'useful'. How powerful is the magnet in a compass.

Is the earths magnetic field not useful.

 

[Juice Terry]

I was actually talking about magnets repelling each other.

So was I, magnets only repel each other when they brought together by an external force such as you or .......

If you drop the magnet close enough to the first they will still repel each other. You are not doing the work then are you?

Gravity, the earth is just a great big magnet.

ETA:

Do you manually have to turn the needle in a compass so it points north? Or is the 'work' done by magnetic forces?

The needle is a compass never moves it always points north no work required, thats the whole point of a compass. The person holding the compass may move around it but the needle never moves.

 

[FridgeMagnet]

"Perpetual" means "for ever" not "for a really long time".

 

[WouldBe]

The needle is a compass never moves it always points north no work required, thats the whole point of a compass. The person holding the compass may move around it but the needle never moves.

So you have never seen a compass needle overshoot then move in the opposite direction before finally coming to a rest pointing north then?

 

[WouldBe]

"Perpetual" means "for ever" not "for a really long time".

So in that case absolutely nothing is perpetual and it's pointless talking about such things and even more pointless having a word for it.

However somethings are more 'perpetual' than others.

 

[Crispy]

Things do not defy gravity without some form of energy being put in. In a tug-of-war the rope may not be moving but 'work' is definately still being done.

I can defy gravity by standing on a brick. Electrostatic repulsion between brick atoms and Crispy atoms (almost exactly the same force as that you get out of a magnet) keeps me from falling through it and onto the ground. No mystery at all. And no 'work' done.

 

[Good Intentions]

So in that case absolutely nothing is perpetual and it's pointless talking about such things and even more pointless having a word for it.

However somethings are more 'perpetual' than others.

Stop being facetious

 

[WouldBe]

Just as much 'work' is done if the two bars are touching against each other, supporting each other. Magnetism just allows action at a distance, which seems freaky - but is completely natural. After all, if the two bars support each other by touvhing, they're not actually touching - their respective molecules are repelling each other electrostatically. If you zoomed right in, you see that the atoms are actually 'floating' relative miles away from each other - and there's no energy being used up to make them do so either.

That we know of.

Someone has already defined work as involving movement.

Electrons spin on their axis and rotate around the nucleus. Therefore by that definition 'work' is being done, as movement is occuring, which requires energy.

 

[WouldBe]

I can defy gravity by standing on a brick. Electrostatic repulsion between brick atoms and Crispy atoms (almost exactly the same force as that you get out of a magnet) keeps me from falling through it and onto the ground. No mystery at all. And no 'work' done.

Falling through a brick and hovering in the air are 2 completely different things.

Does a maglev train do no work when it is stationary but hovering above the tracks.

What about that picture in New Scientist some years back where the disk of super conductor is hovering above a permanent magnet. Is no 'work' being done there?

 

[WouldBe]

Stop being facetious

Perhaps if some people stopped being so pedantic I wouldn't need to be.

 

[Crispy]

That we know of.

Someone has already defined work as involving movement.

Electrons spin on their axis and rotate around the nucleus. Therefore by that definition 'work' is being done, as movement is occuring, which requires energy.

Ok, I'll try not to be condescending here, but

a)electrons are not little spinning balls flying around other little balls

and

b)even if they were, they wouldn't need energy to keep them going. check out the planets - they've been spinning round the sun for billions of years and there's nobody giving them a push.

-

Scientists have nailed down a pretty solid definition of the words 'matter' and 'energy' and your reasoning is not based on that, I'm afraid. 'Common sense' may make magnets seem like magic, but they're as magic as things falling when you drop them.

'Work', strictly speaking, involves change in movement. Eg, speeding something up, slowing something down, changing something's direction. You do work when you heat up water by making the atoms of that water move faster (that's simplified, but pretty accurate).

 

[Good Intentions]

Perhaps if some people stopped being so pedantic I wouldn't need to be.

In case you hadn't noticed, science is built on being pedantic. Otherwise bridges wouldn't stay standing. Gravity is one unforgiving motherfucker.

 

[Crispy]

Falling through a brick and hovering in the air are 2 completely different things.

No, they are two almost identical things - it's just that the scales are different. The large scale effect seems freaky because you can see it happening. Me and the brick are made of 99.9999999999999% absolutely fuck all. The remaining .00000000000000001% is held together by electrostatic forces. It is these force that prevent me falling through the brick. Electrostatic and magnetic forces are both manifestations of the same underlying force - electromagnetism.

Now if you want to know what that really is - then you're getting into 12-smartest-people-in-the-world territory, and even they're not sure.

EDIT : A maglev train does some work while standing still, but that's only because it uses electromagnets that need a constant supply of energy.

 

[stdPikachu]

Forget it guys, he clearly has no concept of the laws of physics as evidenced by his "but MY idea for a perpetual motion machine WILL work, damnit!" mantra.

The original question - can magnets be used for renewable energy - was a valid one, and people pointed out to xes that we alerady use magnets as a source of renewable energy, such as hydroelectricity. Perpetual motion machines (i.e. energy that's not just renewable but energy that's actually created from nothing) are physically impossible.

BTW, I've got some spare entropy going cheap if anyone's interested.

 

[WouldBe]

they've been spinning round the sun for billions of years and there's nobody giving them a push.

The sun's gravity is giving them a push or rather a pull.

Scientists have nailed down a pretty solid definition of the words 'matter' and 'energy' and your reasoning is not based on that, I'm afraid. 'Common sense' may make magnets seem like magic, but they're as magic as things falling when you drop them.

My reasoning is based on observation which is behind most scientific logic. If you want to get something to hover in the air you have to expend energy, wether that be by hoisting the object up using a rope and pulley, burning fuel in a helicopter or using electricity in a maglev train. By observation it is possible to float 2 magnets above each other so energy must be being expended.

 

[FridgeMagnet]

Well, we don't use them as a *source* of renewable energy, we use them to turn it into a more useful form.

 

[WouldBe]

Forget it guys, he clearly has no concept of the laws of physics as evidenced by his "but MY idea for a perpetual motion machine WILL work, damnit!" mantra.

*snigger*

Perpetual motion machines (i.e. energy that's not just renewable but energy that's actually created from nothing) are physically impossible.

Have you read the big bang thread?

One of the theories is that the universe was created from nothing and certainly contains plenty of energy sources. So by your definition the universe is a 'perpetual motion machine'. Oops.

 

[WouldBe]

Well, we don't use them as a *source* of renewable energy, we use them to turn it into a more useful form.

But we do that with all *sources* of energy. Radios and TV's don't work very well on coal.

 

[Crispy]

If you want to get something to hover in the air you have to expend energy, wether that be by hoisting the object up using a rope and pulley, burning fuel in a helicopter or using electricity in a maglev train. By observation it is possible to float 2 magnets above each other so energy must be being expended.

Ah, here's the crux of it. To raise something in the air, you do indeed have to use some energy. However, once you've pulled on your pulley, you can tie the rope off and it will hang there forever - consuming no energy at all.

Same with two magnets. You will find that to push two magnets into a position such that one will move upwards and then hang there, you must exert energy against the magnetic fields. Once one is hanging around up there, no energy is being used. Think of magnetic fields like invisible rope, not invisible muscles.

 

[Crispy]

But we do that with all *sources* of energy. Radios and TV's don't work very well on coal.

Nope they run on electricity, generated by moving wires through magnetic fields. They move because hot steam pushes a turbine round and round. The steam is hot because we burnt coal underneath it.

 

[gurrier]

One of the theories is that the universe was created from nothing and certainly contains plenty of energy sources. So by your definition the universe is a 'perpetual motion machine'. Oops.

It came from a singularity, not nothing and an equal amount of matter/energy exist in the universe today as did an instant after the big bang (law of conservation of energy/matter). The universe is simply following the second law of thermodynamics and increasing the entropy of the system.

 

[WouldBe]

Link to super conductors.

A conductor will oppose any change in externally applied magnetic field. Circulating currents will be induced to oppose the buildup of magnetic field in the conductor

For a current to be induced electrons must be moving hence 'work' is being done.

As long as you keep the super conductor below it's critical temperature the induced currents will continue to flow and the magnet will continue to levitate above it.

As 'work' is being done and energy is being expended, in producing the repulsive magnetic field, where does this energy come from?

 

[gurrier]

For a current to be induced electrons must be moving hence 'work' is being done.

As long as you keep the super conductor below it's critical temperature the induced currents will continue to flow and the magnet will continue to levitate above it.

As 'work' is being done and energy is being expended, in producing the repulsive magnetic field, where does this energy come from?

Work is not being done (remember that work is the product of the change in the displacement and the force). If there is no change in the displacement, no work is done.

The energy is extracted from the super-conductor in the form of heat.

 

[ICB]

Ah, here's the crux of it. To raise something in the air, you do indeed have to use some energy. However, once you've pulled on your pulley, you can tie the rope off and it will hang there forever - consuming no energy at all.

You wouldn't say that if you were the rope, or the thing it was tied off to.

There are a few too many people sounding like they've got all the answers on here. Show me your unified field theory then.

 

[WouldBe]

Work is not being done (remember that work is the product of the change in the displacement and the force). If there is no change in the displacement, no work is done.

The energy is extracted from the super-conductor in the form of heat.

A current is induced in the super conductor.

A current cannot exist without a voltage to drive it.

If you have voltage and current you have power (watts).

This power, being induced comes from the magnet hovering over the superconductor.

So either

a) the magnet has to 'discharge' itself becoming rapidly weaker in the process.
b) the magnet has to change it's matter to energy becoming lighter in the process.
c) the magnet has to 'recharge' itself by some means.

Although magnets do get weaker over time it is normally a very long period. I have never come across a case where a magnet becomes lighter due to converting it's matter into energy so that only leaves option (c)

So how does a magnet 'recharge' itself?

 

[Crispy]

You wouldn't say that if you were the rope, or the thing it was tied off to.

There are a few too many people sounding like they've got all the answers on here. Show me your unified field theory then.

Well, no, I wouldn't say that if I was the rope, because the human body consumes energy to maintain a position, grip hands etc. However, a tied up rope is just as inert as a pile of rocks. No energy being consumed or transformed anywhere.

I'm not trying to be some sort of smartarse by the way, these are pretty basic universal physics situations that are well-understood by science.