Introduction to
DIELECTRICITY AND CAPACITANCE
by Eric Dollard
CAPACITANCE
The phenomena of capacitance is a type of electrical
energy storage in the form of a field in an enclosed space. This
space is typically bounded by two parallel metallic plates or two
metallic foils on an intervening insulator or dielectric. A
nearly infinite variety of more complex structures can exhibit
capacity, as long as a difference in electric potential exists
between various areas of the structure. The oscillating coil
represents one possibility as to a capacitor of more complex
form, and will be presented here.
CAPACITANCE INADEQUATELY EXPLAINED
The perception of capacitance as used today is wholly
inadequate for the proper understanding of this effect. Steinmetz
mentions this in his introductory book Electric Discharges, Waves
and Impulses. To quote, "Unfortunately, to large extent in
dealing with dielectric fields the prehistoric conception of the
electrostatic charge (electron) on the conductor still exists,
and by its use destroys the analogy between the two components of
the electric field, the magnetic and the dielectric, and makes
the consideration of dielectric fields unnecessarily
complicated."
LINES OF FORCE AS REPRESENTATION OF DIELECTRICITY
Steinmetz continues, "There is obviously no more
sense in thinking of the capacity current as current which
charges the conductor with a quantity of electricity, than there
is of speaking of the inductance voltage as charging the
conductor with a quantity of magnetism. But the latter
conception, together with the notion of a quantity of magnetism,
etc., has vanished since Faraday's representation of the magnetic
field by lines of force."
THE LAWS OF LINES OF FORCE
All the lines of magnetic force are closed upon
themselves, all dielectric lines of force terminate on
conductors, but may form closed loops in electromagnetic
radiation. These represent the basic laws of lines of force. It
can be seen from these laws that any line of force cannot just
end in space.
FARADAY & LINES OF FORCE THEORY
Farady felt strongly that action at a distance is not
possible thru empty space, or in other words, "matter cannot
act where it is not." He considered space pervaded with
lines of force. Almost everyone is familiar with the patterns
formed by iron filings around a magnet. These filings act as
numerous tiny compasses and orientate themselves along the lines
of force existing around the poles of the magnet. Experiment has
indicated that a magnetic field does possess a fibrous construct.
By passing a coil of wire thru a strong magnetic field and
listening to the coil output in headphones, the experimenter will
notice a scraping noise. J. J. Thompson performed further
experiments involving the ionization of gases that indicate the
field is not continuous but fibrous (electricity and matter,
1906).
PHYSICAL CHARACTERISTICS OF LINES OF FORCE
Consider the space between poles of a magnet or
capacitor as full of lines of electric force. See Fig.1. These
lines of force act as a quantity of stretched and mutually
repellent springs. Anyone who has pushed together the like poles
of two magnets has felt this springy mass. Observe Fig.2. Notice
the lines of force are more dense along AB in between poles, and
that more lines on A are facing B than are projecting outwards to
infinity. Consider the effect of the lines of force on A. These
lines are in a state of tension and pull on A. Because more re
pulling on A towards B than those pulling on A away from B, we
have the phenomena of physical attraction. Now observe Fig. 3.
Notice now that the poles are like rather than unlike, more or
all lines pull A away from B; the phenomena of physical
repulsion.
MASS ASSOCIATED WITH LINES OF FORCE IN MOTION
The line of force can be more clearly understood by
representing it as a tube of force or a long thin cylinder.
Maxwell presented the idea the tension of a tube of force is
representative of electric force (volts/inch), and in addition to
this tension, there is a medium through which these tubes pass.
There exists a hydrostatic pressure against this media or ether.
The value of this pressure is one half the product of dielectric
and magnetic density. Then there is a pressure at right angles to
an electric tube of force. If through the growth of a field the
tubes of force spread sideways or in width, the broadside drag
through the medium represents the magnetic reaction to growth in
intensity of an electric current. However, if a tube of force is
caused to move endwise, it will glide through the medium with
little or no drag as little surface is offered. This possibly
explains why no magnetic field is associated with certain
experiments performed by Tesla involving the movement of energy
with no accompanying magnetic field.
INDUCTANCE AS AN ANALOGY TO CAPACITY
Much of the mystery surrounding the workings of capacity
can be cleared by close examination of inductance and how it can
give rise to dielectric phenomena. Inductance represents energy
storage in space as a magnetic field. The lines of force
orientate themselves in close loops surrounding the axis of
current flow that has given rise to them. The large the space
between this current and its images or reflections, the more
energy that can be stored in the resulting field.
MECHANISM OF STORING ENERGY MAGNETICALLY
The process of pushing these lines or loops outward,
causing them to stretch, represents storing energy as in rubber
band. A given current strength will hold a loop of force at a
given distance from conductor passing current hence no energy
movement. If the flow of current increases, energy is absorbed by
the field as the loops are then pushed outward at a corresponding
velocity. Because energy is in motion an E.M.F. must accompany
the current flow in order for it to represent power. The
magnitude of this EMF exactly corresponds to the velocity of the
field. Then if the current ceases changing in magnitude thereby
becoming constant, no EMF accompanies it, as no power is being
absorbed. However, if the current decreases and represents then a
negative velocity of field as the loops contract. Because the EMF
corresponds exactly to velocity it reverses polarity and thereby
reverses power so it now moves out of the field and into the
current. Since no power is required to maintain a field, only
current, the static or stationary field, represents stored
energy.
THE LIMITS OF ZERO AND INFINITY
Many interesting features of inductance manifest
themselves in the two limiting cases of trapping the energy or
releasing it instantly. Since the power supply driving the
current has resistance, when it is switched off the inductance
drains its energy into this resistance that concerts it into the
form of heat. We will assume a perfect inductor that has no self
resistance. If we remove the current supply by shorting the
terminals of the inductor we have isolated it without
interrupting any current. Since the collapse of field produces
EMF this EMF will tend to manifest. However, a short circuit will
not allow an EMF to develop across it as it is zero resistance by
definition. No EMF can combine with current to form power,
therefore, the energy will remain in the field. Any attempt to
collapse forces increased currents which pushes it right back out
This is one form of storage of energy.
INSTANT ENERGY RELEASE AS INFINITY
Very interesting (and dangerous) phenomena manifest
themselves when the current path is interrupted, thereby causing
infinite resistance to appear. In this case resistance is best
represented by its inverse, conductance. The conductance is then
zero. Because the current vanished instantly the field collapses
at a velocity approaching that of light. As EMF is directly
related to velocity of flux, i tends towards infinity. Very
powerful effects are produced because the field is attempting to
maintain current by producing whatever EMF required. If a
considerable amount of energy exists, say several kilowatt hours*
(250 KWH for lightning stroke), the ensuing discharge can produce
most profound effects and can completely destroy inadequately
protected apparatus.* The energy utilized by an average household
in the course of one day.
ANOTHER FORM OF ENERGY APPEARS
Through the rapid discharge of inductance a new force
field appears that reduces the rate of inductive EMF formation.
This field is also represented by lines of force but these are of
a different nature than those of magnetism. These lines of force
are not a manifestation of current flow but of an electric
compression or tension. This tension is termed voltage or
potential difference.
DIELECTRIC ENERGY STORAGE SPATIALLY DIFFERENT THAN
MAGNETIC ENERGY
STORAGE
Unlike magnetism the energy is forced or compressed
inwards rather than outwards. Dielectric lines of force push
inward into internal space and along axis, rather than pushed
outward broadside to axis as in the magnetic field. Because the
lines are mutually repellent certain amounts of broadside or
transverse motion can be expected but the phenomena is basically
longitudinal. This gives rise to an interesting paradox that will
be noticed with capacity. This is that the smaller the space
bounded by the conducting structure the more energy that can be
stored. This is the exact opposite of magnetism. With magnetism,
the units volumes of energy can be though of as working in
parallel but the unit volumes of energy in association with
dielectricity can be thought of as working in series.
VOLTAGE IS TO DIELECTRICITY AS CURRENT IS TO MAGNETISM
With inductance the reaction to change of field is the
production of voltage. The current is proportionate to the field
strength only and not velocity of field. With capacity the field
is produced not by current but voltage. This voltage must be
accompanied by current in order for power to exist. The reaction
of capacitance to change of applied force is the production of
current. The current is directly proportional to the velocity of
field strength. When voltage increases a reaction current flows
into capacitance and thereby energy accumulates. If voltage does
not change no current flows and the capacitance stores the energy
which produced the field. If the voltage decreases then the
reaction current reverses and energy flows out of the dielectric
field.As the voltage is withdrawn the compression within the
bounded space is relieved. When the energy is fully dissipated
the lines of force vanish.
AGAIN THE LIMITS ZERO AND INFINITY
Because the power supply which provided charging voltage
has internal conductance, after it is switched off the current
leaking through conductance drains the dielectric energy and
converts it to heat. We will assume a perfect capacitance having
no leak conductance. If we completely disconnect the voltage
supply by open circuiting the terminals of the capacitor, no path
for current flow exists by definition of an open circuit. If the
field tends to expand it will tend towards the production of
current. However, an open circuit will not allow the flow of
current as it has zero conductance. Then any attempt towards
field expansion raises the voltage which pushes the field back
inwards. Therefore, energy will remain stored in the field. This
energy can be drawn for use at any time. This is another form of
energy storage.
INSTANT ENERGY RELEASE AS INFINITY
Phenomena of enormous magnitude manifest themselves when
the criteria for voltage or potential difference is instantly
disrupted, as with a short circuit. The effect is analogous with
the open circuit of inductive current. Because the forcing
voltage is instantly withdrawn the field explodes against the
bounding conductors with a velocity that may exceed light.
Because the current is directly related to the velocity of field
it jumps to infinity in its attempt to produce finite voltage
across zero resistance. If considerable energy had resided in the
dielectric force field, again let us say several KWH the
resulting explosion has almost inconceivable violence and can
vaporize a conductor of substantial thickness instantly.
Dielectric discharges of great speed and energy represent one of
the most unpleasant experiences the electrical engineer
encounters in practice.
ENERGY RETURNS TO MAGNETIC FORM
The powerful currents produced by the sudden expansion
of a dielectric field naturally give rise to magnetic energy. The
inertia of the magnetic field limits the rise of current to a
realistic value. The capacitance dumps all its energy back into
the magnetic field and the whole process starts over again. The
inverse of the product of magnetic storage capacity and
dielectric storage capacity represents the frequency or pitch at
which this energy interchange occurs. This pitch may or may not
contain overtones depending on the extent of conductors bounding
the energies.
CHARACTERISTIC IMPEDANCE AS REPRESENTATION OF PULSATION
OF ENERGY FIELD
The ratio of magnetic storage ability to that of the
dielectric is called the characteristic impedance. This gives the
ratio of maximum voltage to maximum current in the oscillatory
structure. However, as the magnetic energy storage is outward and
the dielectric storage is inward the total or double energy field
pulsates in shape or size.The axis of this pulsation of force is
the impedance of the system displaying oscillations and pulsation
occurs at the frequency of oscillation.
ENERGY INTO MATTER
As the voltage or impedance is increased the emphasis is
on the inward flux. If the impedance is high and rate of change
is fast enough (perfect overtone series), it would seem possible
the compression of the energy would transform it into matter and
the reconversion of this matter into energy may or may not
synchronize with the cycle of oscillation. This is what may be
considered supercapacitance, that is, stable long term conversion
into matter.
MISCONCEPTIONS OF PRESENT THEORY OF CAPACITANCE
The misconception that capacitance is the result of
accumulating electrons has seriously distorted our view of
dielectric phenomena. Also the theory of the velocity of light as
a limit of energy flow, while adequate for magnetic force and
material velocity, limits our ability to visualize or understand
certain possibilities in electric phenomena. The true workings of
free space capacitance can be best illustrated by the following
example. It has been previously stated that dielectric lines of
force must terminate on conductors. No line of force can end in
space. If we take any conductor and remove it to the most remote
portion of the universe, no lines of force can extend from this
electrode to other conductors. It can have no free space
capacity, regardless of the size of the electrode, therefore it
can store no energy. This indicates that the free space
capacitance of an object is the sum mutual capacity of it to all
the conducting objects of the universe.
FREE SPACE INDUCTANCE IS INFINITE
Steinmetz in his book on the general or unified behavior
of electricity The Theory and Calculation of Transient Electric
Phenomena and Oscillation, points out that the inductance of any
unit length of an isolated filamentary conductor must be
infinite. Because no image currents exist to contain the magnetic
field it can grow to infinite size. This large quantity of energy
cannot be quickly retrieved due to the finite velocity of
propagation of the magnetic field. This gives a non reactive or
energy component to the inductance which is called
electromagnetic radiation.
WORK OF TESLA, STEINMETZ AND FARDAY
In the aforementioned books of Steinmetz he develops
some rather unique equations for capacity. Tesla devoted an
enormous portion of his efforts to dielectric phenomena and made
numerous remarkable discoveries in this area. Much of this work
is yet to be fully uncovered. It is my contention that the
phenomena of dielectricity is wide open for profound discovery.
It is ironic that we have abandoned the lines of force concept
associated with a phenomena measure in the units called farads
after Farady, whose insight into forces and fields has led to the
possibility of visualization of the electrical phenomena.
QUESTION AS TO THE VELOCITY OF DIELECTRIC FLUX
It has been stated that all magnetic lines of force must
be closed upon themselves, and that all dielectric lines of force
must terminate upon a conducting surface. It can be inferred from
these two basic laws that no line of force can terminate in free
space. This created an interesting question as to the state of
dielectric flux lines before the field has had time to propagate
to the neutral conductor. During this time it would seem that the
lines of force, not having reached the distant neutral conductor
would end in space at their advancing wave front. It could be
concluded that either the lines of force propagate instantly or
always exists and are modified or conjugate space exists within
the same boundaries as ordinary space. The properties of lines of
force within this conjugate space may not obey the laws of
normally conceived space.
IMPORTANT REFERENCE MATERIAL
1. Electricity and Matter, J. J. Thompson, New York, l906,
Scribner's Sons, and l904, Yale University.
2. Elementary Lecture on Electric Discharges, Waves, and Impulses
and other Transients, C. P. Steinmetz, second edition, 1914,
McGraw-Hill.
3. Theory and Calculation of Transient Electric Phenomena and
Oscillations, C. P. Steinmetz, third edition, l920, McGraw-Hill.
Section III Transients in Space, Chapter VIII, Velocity of
Propagation of Electric Field.
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