Engineers and physicists have invented many
ways to depict fields. A vector field such
as the E-field is usually represented
by an arrow. Traditionally, the vector field
intensity (or strength) would be represented
by the density of arrows per unit length along
a line orthogonal to the streamline (i.e. along
the equipotential). Equipotentials and streamlines
are always orthogonal to each other, which
is a consequence of the mathematical relation .
Now that we use powerful computers and software
to make complicated electromagnetic computations,
we got accustomed to representing the field
magnitude either by the length of the arrow
or by its color, the latter being preferable.
These methods are easier to program and can
represent practically any field, however
complicated it may be.
A scalar field, on the other hand, such
as the electric potential V, used
to be and still is represented by equipotential
lines or surfaces, which are the geometrical
place of all points with equal potentials.
For example, the equipotential surfaces of
a point charge are spheres centered onto
the charge itself. The equipotential surfaces
of a line charge are cylinders, which are
coaxial with the line charge. In the cross-section
orthogonal to the charge, they appear as
equipotential lines: concentric circles.
Typically, the equipotentials are plotted
at equal intervals, for example, every 10
V.
Still, the 2-D plot of the E-field
magnitude or the potential along a line remains
the most accurate illustration method.
Choose a set of images illustrating one
of the following electric structures:
Ø Charged
Sphere
Ø Cross-section
of Charged Cylinder
Ø Cross-section
of Parallel-plate Line
Ø Cross-section
of Coaxial Line
Ø Cross-section
of Two-wire Line |