How do magnets pull things if magnetic forces are incapable of doing work?

[Raziel2701]

When a magnet pulls a paperclip, what exactly is doing work on the paperclip? It cannot be a magnetic force can it? I thought it was a very strong statement that I read in my intro physics book and even Griffiths(pg. 207) that magnetic forces do no work. So what is responsible for accelerating a paperclip towards a magnet?

Is it something related to the changing magnetic flux? Is there an electric field somewhere doing the work?

Thanks.

 

[Vorde]

Try reading this, ask if you still have questions afterwards:

https://www.physicsforums.com/showthread.php?t=170447

 

[Raziel2701]

I think the guy on the second part of the thread who's touching on spin was getting closer to the point of my question. I still don't know what's responsible for the work we see when a paperclip gets pulled in by a magnet.

 

[mfb]

With magnetic fields, you always have charges which move in some way (spin is similar to a movement in that respect). Moving charges in magnetic fields are equivalent to stationary charges in a field which has an electric component.

 

[sardar]

I can provide some clarification on this topic. It is true that magnetic forces themselves do not do work. Work is defined as the transfer of energy from one object to another, and magnetic forces do not transfer energy. Instead, they exert a force on an object without changing the object's energy.

However, this does not mean that a magnet cannot pull an object towards it. When a magnet attracts a paperclip, it is not the magnetic force itself that is doing the work, but rather the magnetic field created by the magnet. This magnetic field interacts with the magnetic field of the paperclip, causing a force to be exerted on the paperclip. This force then accelerates the paperclip towards the magnet.

The reason why magnetic forces do not do work is because they are conservative forces. This means that the work done by the force is independent of the path taken by the object. In the case of a magnet and a paperclip, the work done is the same whether the paperclip is pulled directly towards the magnet or if it takes a longer, more circuitous route.

The changing magnetic flux you mentioned is also related to this concept. When a magnet moves, the magnetic flux changes, which can induce an electric field. This electric field can then do work on the paperclip, causing it to accelerate towards the magnet.

In summary, while magnetic forces themselves do not do work, they can still cause an object to accelerate towards a magnet through the interaction of magnetic fields. It is the magnetic field and potential for a changing magnetic flux that are responsible for the acceleration of the paperclip. I hope this helps clarify any confusion.