Magnetic Field
A vector field generated by moving electric charges, electric currents, or intrinsic magnetic moments that exerts magnetic forces on other moving charges and dipoles.
Governing formula
F_mag = q (v × B), B = μ₀ I / (2π r)
SI unit
T (Tesla = N/(A·m))
In depth
Magnetic field lines form continuous closed loops without beginning or end, reflecting Gauss's law for magnetism (∇ · B = 0). The direction of magnetic force on a moving charge is perpendicular to both the particle's velocity vector and the magnetic field vector.
Examples in the real world
Earth's magnetic field (~50 μT) deflecting solar wind particles, or superconducting MRI magnets generating intense 3 Tesla diagnostic fields.