A magnetic field is a physical field that describes the magnetic influence exerted on moving electric charges, electric currents, and magnetic materials. It is a vector field, meaning it has both magnitude and direction at every point in space
. Magnetic fields are produced primarily by moving electric charges (electric currents) and the intrinsic magnetic moments of elementary particles such as electrons due to their spin. For example, when an electric current flows through a wire, it creates a magnetic field around the wire
. The magnetic field exerts a force on moving charges perpendicular to both their velocity and the direction of the magnetic field. This force causes charged particles to move in circular or helical paths, which is the principle behind electric motors and generators
. Magnetic fields can be static (unchanging in time) or dynamic (changing with time). Around a permanent magnet or a steady current, the magnetic field is stationary. Around an alternating current, the magnetic field continuously changes in magnitude and direction
. Magnetic fields are often visualized by lines of magnetic flux, which emerge from the north pole of a magnet and enter the south pole, forming closed loops. The density of these lines indicates the strength of the magnetic field
. In summary, a magnetic field is an invisible force field generated by moving electric charges or magnetized materials, influencing other moving charges and magnetic objects in its vicinity
