So there's this sentence in a book I am reading. It states "When a charged particle is placed within a magnetic field, despite the magnetic force acting on the particle, there will be no change in the total energy content of the particle. As the force acts along the radius, it is a non-effective force. So, no work is done by the particle. Hence, the change in total energy content is zero."
I'd really like to understand what this means. If someone could explain what they're trying to say here.
My first thought was that this is nothing complicated and a simple iteration of the force times component of displacement theorem. Since the magnetic field acts perpendicular to the charge the force also acts perpendicular to the electric field. So there's no resultant work.