¾ With the modern knowledge about the structure of matter
we know that electric charges come from elementary
particles: negatively charged electron and positively charged
proton. In nuclei there are also neutron with no charge.
Interaction between charges: two positive charges or two
negative charges repel each other. A positive charge and a
negative charge attract each other. This interaction is called the
static electric interaction.
Electrically conductive shoes provide protection against the
buildup of static electricity. Employees working in explosive and
hazardous locations such as explosives manufacturing facilities or
grain elevators must wear conductive shoes to reduce the risk of
static electricity buildup on the body that could produce a spark and
cause an explosion or fire. Foot powder should not be used in
conjunction with protective conductive footwear because it
provides insulation, reducing the conductive ability of the shoes.
The electromagnetic power is generated and radiated by antennas. Timevarying current radiates electromagnetic waves (radiated electromagnetic fields). Radiation pattern, beam width, directivity, and other major characteristics can be studied using Maxwell’s equations, see Section 2.2. We use the vectors of the electric field intensity E, electric flux density D, magnetic field intensity H, and magnetic flux density B. The constitutive equations are D = εE and B = µH where ε is the permittivity; µ is the permiability. It was shown in Section 2.