That is a simplified description for static magnetic fields, with free charges moving in them. Your system does not have that.Now, I'm not sure if I misunderstood the textbook but I read that magnetic fields and forces don't actually do any work.
That's true for classical electrodynamics but not always the case in certain quantum mechanical situations. E.g. if you were to place a charged particle at rest in a non-uniform magnetic field then the magnetic field would do work on the charged particle because it has a magnetic moment and thus acts as a microscopic bar magnet.DAPOS said:Now, I'm not sure if I misunderstood the textbook but I read that magnetic fields and forces don't actually do any work.
Work is being done, just not by the magnetic field. It's the electric field of the charges which make up the iron fillings which are doing the work. This is all explained in the following two articlesDAPOS said:How is this the case? Consider a bar magnetic and some iron filings. If you use the magnet to attract the filings towards it wouldn't some sort of work be done? Thanks.
You're most welcome. I love the American Journal of Physics. It's my favorite physics journal because I love thinking about the foundations of physics.DAPOS said:Great stuff. Thanks for that. I'm not sure that I'll be doing much further reading on the subject at the moment. This is great for now.
You're most welcome. I finally realized that you can upload files into posts that can be read by anyone reasding the post. I greatly enjoy helping people learn physics and math in anyway that I'm able to. It just feels so good to do so. Ever notice that yourself? :tongue:DAPOS said:Brilliant. Thanks for that and I'll be sure to ask for those if I ever feel the need to read on.
In physics, work is defined as the change in energy that occurs when a force is applied to an object and the object moves a certain distance in the direction of the force.
Magnetic forces/fields do not do work because they do not cause a change in energy in the objects they act upon. This is because the force of a magnetic field is always perpendicular to the direction of motion of the object, so there is no component of force in the direction of motion to cause a change in energy.
Yes, magnetic forces/fields can indirectly do work by causing a change in the direction of motion or velocity of an object. This change in direction can then lead to a change in energy, but the magnetic force/field itself is not directly responsible for the work done.
The work done by a magnetic force/field can be calculated by multiplying the magnitude of the magnetic force by the displacement of the object in the direction of the force. However, this calculation will always result in a value of zero since the displacement is always perpendicular to the force.
Yes, one example is the motion of charged particles in a magnetic field. The magnetic force will cause the particles to move in a circular path, but since the force is perpendicular to the motion, no work is done on the particles.