Do Magnetic Fields Actually Perform Work?

[Substance D]

I'm confused as to wither or not magnetic fields do work. From reading the forums, as well as my textbook and online resources there seems to be conflicting answers. We talk about magnetic energy, and how work relates to change in energy but then I hear that magnetic fields do no work. Could someone please clarify this for me.

Thank you :)

ps. My question stems from reading about so called free-energy devices that use magnetic fields. I was trying to debunk them by stating that according to my textbook magnetic fields do no work, but as I looked into it I kept seeing that I was really confused on the matter and I believe it stems from my confusion over terms.

 

[Born2bwire]

Magnetic fields can do work. The easiest demonstration of this is the fact that two magnets will pull each other together when in close enough proximity. I think your confusion may deal with the fact that magnetic fields are conservative. If I hold two magnets at a distance of 5 inches apart, release them and they pull together, then they do work. If I then separate them and move them back to a distance of 5 inches, I do the exact opposite amount of work that they did pulling themselves together. So the net work of the system is 0.

In most systems, we will end up having the magnets do a net work of 0, eventually the energy that we extract from the fields gets put back in or no real work is done in the first place. Otherwise, we will eventually exhaust the magnet. Another example is that of the Lorentz force. The force contribution from the magnetic field is always perpendicular to the velocity of the charged particle. So in that case the work is always zero since it is perpendicular to the path of motion.

 

[astrokreng]

Hello,

Thank you for your question. I can understand your confusion regarding the relationship between magnetism, work, and energy. Let me try to clarify this for you.

Firstly, it is important to understand that magnetism is a fundamental force of nature, just like gravity or electricity. It is caused by the movement of electrically charged particles, such as electrons, within a material or in a magnetic field.

Now, when we talk about work and energy, we are referring to the ability to do work or produce a change in a system. In the case of magnetism, this can be seen in the form of magnetic energy. Magnetic energy is the potential energy that is stored in a magnetic field. This energy can be converted into other forms, such as kinetic energy, when a magnetic field interacts with a moving object.

However, it is important to note that magnetic fields themselves do not do work. Work is defined as the force applied to an object multiplied by the distance over which the force is applied. In the case of a magnetic field, there is no physical contact or force being applied to an object, so no work is being done.

This may be where the confusion lies when it comes to free-energy devices that claim to use magnetic fields. These devices often claim to generate more energy than they consume, which goes against the laws of thermodynamics. In reality, these devices are likely using other sources of energy, such as electricity, to power the magnetic field and produce the desired effects.

In summary, while magnetic fields do not do work, they do contain potential energy that can be harnessed and converted into other forms of energy. I hope this helps to clarify your understanding of magnetism, work, and energy.