The fundamental difference between electricity and magnetism is that
- electric field is produced by electric charges (it does not matter if the charges are stationary or moving);
- but magnetic field is produced by moving electric charges only. There are no magnetic charges. Thus we need to have electric charge (positive or negative), and if the electric charge is moving then it prodof eleuces magnetic field (of cause it also produces electric field). If the charge is not moving, then there is no magnetic field (only electric field).
Similarly, the interaction of electric charges with magnetic field have the same pattern:
- if the charge is stationary -> there is no magnetic force acting on the charge
- if the charge is moving -> then there is magnetic force acting on the charge.
Direction of the magnetic force: the magnetic force on the moving electric charge is always perpendicuar to the direction of magnetic field and the direction of velocity of the charge. As a results the magnetic force can change only the direction of velocity of the charge but not its magnitude. This also means that the magnetic force cannot change the kinetic energy of the electric charge: the work produced by magnetic force on moving charge is zero.
Below you can find animations of different concepts related to magnetism.