Conservation of energy and magnets

In summary, a precessing magnet will eventually slow down and stand straight up, reaching its lowest potential energy due to the shedding of light through its magnetic field. However, if the magnet is already standing straight up, there will be no change in its potential energy and no need to emit light. The forces on the magnet cancel out, and there is no acceleration or electromagnetic radiation. Therefore, the magnet is not emitting or absorbing photons. The force is transmitted through changes in the magnetic field, not through light.
  • #1
nhmllr
185
1
Things with a magnetic field constantly shed light. This is why a precessing magnet will slow down until it stands straight up, giving it the lowest potential energy. But if the magnet is standing straight up, it has no way to have less potential energy, but I would think that it would continue to have a magnetic pull, which would necessitate it the keep shedding photons/energy. But then what about the conservation of energy?

Thanks
 
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  • #2
If the magnet is aligned in it's magnetic field ("straight up" in your reference frame) then there is a "pull" yes, in that there are forces on it. But the forces are symmetric, they cancel out; there is no net force on (and thus no acceleration of) the magnet. A static (non-moving) magnet does not produce a change in flux, so there is no electromagnetic radiation (i.e. no light).
 
  • #3
Pythagorean said:
If the magnet is aligned in it's magnetic field ("straight up" in your reference frame) then there is a "pull" yes, in that there are forces on it. But the forces are symmetric, they cancel out; there is no net force on (and thus no acceleration of) the magnet. A static (non-moving) magnet does not produce a change in flux, so there is no electromagnetic radiation (i.e. no light).

So... The magnet is emitting and absorbing photons equally? Makes sense.
 
  • #4
nhmllr said:
So... The magnet is emitting and absorbing photons equally? Makes sense.

I'm not quite sure there's any argument for emitting in the first place; at least not in a classical scenario. The flux pertains to magnetic field lines, not electromagnetic radiation.
 
  • #5
Pythagorean said:
I'm not quite sure there's any argument for emitting in the first place; at least not in a classical scenario. The flux pertains to magnetic field lines, not electromagnetic radiation.

But the force has to be transmitted somehow, so light would seem like a way to do that.
Although if this is getting out of the range of classical mechanics then I'm content with the given answer.
 
  • #6
Oh wait, light's only emitted when there's a CHANGE in the magnetic field? OHHHHHH OH OH OH I see. That actually makes sense (such as with induction)

Okay I think I get it.
 
  • #7
yes :)
 

1. What is the conservation of energy?

The conservation of energy is a fundamental law of physics that states that energy cannot be created or destroyed, but can only be converted from one form to another. This means that the total energy in a closed system remains constant.

2. How does the conservation of energy relate to magnets?

Magnets are an example of potential energy, which is a type of energy that is stored and can be converted into other forms. When a magnet is attracted to another object, the potential energy is converted into kinetic energy, causing the magnet to move. However, the total energy remains constant.

3. What is the role of magnets in energy conservation?

Magnets play a crucial role in energy conservation by allowing for the efficient conversion of energy from one form to another. For example, magnets are used in motors and generators to convert mechanical energy into electrical energy and vice versa. This helps to conserve energy and reduce waste.

4. Can magnets produce energy?

No, magnets cannot produce energy on their own. They can only convert energy from one form to another. In order to produce energy, an external source is needed, such as a power plant or a renewable energy source like wind or solar.

5. How is the conservation of energy and magnets important for sustainability?

The conservation of energy and the use of magnets in energy conversion are important for sustainability because they help reduce the consumption of non-renewable energy sources and minimize waste. By using magnets to efficiently convert energy, we can decrease our reliance on fossil fuels and move towards a more sustainable future.

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