The four Maxwell's equations at a glance
 
Gauss' law   D   f describes how an electric field is generated by electric charges.
 
Gauss' law for magnetism   B  0 valid for the absence of magnetic charges (also called
magnetic monopoles), analogous to electric charges.

 
B
Faraday's law   E  
describes how a changing magnetic field can create (induce) an
t
electric field.

  
D
Ampère's law with Maxwell's correction   H  J f 
states that magnetic fields can be
t
generated in two ways: by electrical current (this was the original Ampère's law) and by changing
electric fields (this was Maxwell's correction).

E is the electric force field, measured in Volt per meter, and

D is the electric flux field or displacement field, also called the electric induction or the electric
flux density. It is measured in Coulombs per square meter.

H is the magnetic force field or magnetizing field, also called the auxiliary magnetic field, the
magnetic field intensity or just the magnetic field. It is measured in Ampères per meter, and

B is the magnetic flux field, also called the magnetic induction, the magnetic field density or the
magnetic flux density. It is measured in Tesla.
 f is the free charge density, measured in Coulombs per cubic meter.

J f is the free current density, measured in Ampères per square meter.
More to read: J. D. Jackson, Classical Electrodynamics, 3rd ed., John Wiley, New York, 1999.
Added by the editors