Final answer:
In physics, the work done by an external agent on a system that does not lose energy to non-conservative forces results in a change in the system's potential energy and can correspondingly change its kinetic energy due to the conservation of energy principle.
Step-by-step explanation:
Work-Energy Relationship in Physics
In the context of physics and the conservation of energy, the work done by an external agent on a system is often related to changes in the system's potential energy and kinetic energy.
If we assume a dipole in an external electric or magnetic field, and work is done to align it with the field, there will be a decrease in the system's potential energy, which in a lossless system, would correspond to an increase in another form of energy like kinetic energy, radiation, or both.
For example, the formula U = -μ · B demonstrates how the potential energy (U) of a magnetic dipole (represented by its magnetic moment, μ) in an external magnetic field (B) is minimized when the two are aligned.
If a dipole is placed in an inhomogeneous electric field, the work done to move it can be calculated without considering the specific path it takes, thanks to the conservative nature of the electric field.
A key point to understand here is that when an object's potential energy changes due to work being done externally, without any non-conservative forces like friction, the total mechanical energy of the system remains constant according to the conservation of energy principle.
Finally, the change in potential energy of a system, like a charged particle moving in an electric field, corresponds to the work done.
This is because the work required to move the particle is path-independent and equals the potential energy difference, as described by U(r) = k with a reference point taken at infinity.
Thus, when an external agent does work on a system that is not lost to non-conservative forces, that work will be manifested as a change in the potential energy of the system.