Electric Motors And Generators/Magnetic Field Concepts

Magnetic Field Concepts
An electromagnetic field is a region of space in which electrical charges experience forces. The classical definition of the electromagnetic field is given by the following equation


 * $$\mathbf{F}=q\mathbf{E}+q\mathbf{v}\times\mathbf{B}$$

What this equation states, is that an electrical charge of size $q$ experiences a force when in the presence of an electric field denoted by $E$. Furthermore if the charge is moving, with velocity $v$, it will experience a further force if in the presence of a magnetic field denoted by $B$. Therefore the force on a electric charge defines what the electric and magnetic fields are in a given region of space. Without the presence of a charged particle it could never be known what their magnitudes or directions were.

Further Reading on Magnetism

 * See Magnetic field and Magnetic phenomena and Physics Study Guide/Magnetism and Permanent magnets and Current's magnetic effects and Electromagnetism and Magnetism's units.
 * Wikipedia: Magnet and Wikipedia: Magnetic forces and Wikipedia: Magnetism and Wikipedia: Magnetism's origin

Further Reading on Electric Current

 * See Current and Kirchoff's Current Law (KCL) and Current (Physics) and Relationships: voltage, current and resistance.
 * Wikipedia: Current and Wikipedia: DC and Wikipedia: AC.