Current flowing in one direction (dc) must have a closed path or circuit. The current flowing will be proportional to the voltage applied (E) and inversely proportional to the resistance in the circuit (R). Current is abbreviated as (I). So it can be written:
I = E
R or E = IR
which is Ohm’s law.
The voltage force from a battery is steady, giving us dc current. But current flows back and forth when the voltage force comes from an alternator instead of a battery. It is called ac, meaning alternating current, and shows special characteristics.
Ac can appear to “flow” across spaces, like air or glass or plastic if the current (electrons) is allowed to fill a reservoir on one side of the space while emptying from a reservoir on the other side of the space. A reservoir is called a capacitor. The larger the capacitor the more electrons (charge) it can hold. After the capacitor fills up with charge, it can all be released again, coming back out when the voltage reverses.
C, the capacitance, is proportional to the size, A, of the reservoir and inversely proportional to the distance, d, of the space that is the gap, according to this equation:
C = 0.224KA d
The factor K depends on whether the space is just air, or plastic or some other (non-conducting) material. Remember, current cannot appear to pass through a gap if it is dc. But ac current can and the higher the frequency of reversing voltage, the easier the current can pass, which is seen from:
XC = 1 2πfC
Here Xc refers to the resistance of a capacitor, to distinguish it from the resistance of a wire or other conductor. We can see that the bigger the capacitor C is, or the higher the frequency of voltage changes (f), the smaller will be the resistance of the capacitor. And from Ohm’s law, the smaller the resistance, the more current can appear to flow “through” it. A resistance that is frequency-dependent is called an impedance.
The body is full of capacitors, connected in many different ways. In fact, the body as a whole acts like just another capacitor plate on a resonance box, as we saw in Exp. 1. When you connect yourself to a capacitance meter, a medium-size person shows 135 pF (picofarads, or 10-12F). If you stretch out your arms and stand up, the capacitance may go up to 140 pF. If you scrunch yourself up into a ball or if you are a short person, your capacitance will read about 130 pF. These are my own readings taken inside a shielded cage, using a 3001 Capacitance meter (Continental Specialties Corp). The significance of the readings is unknown. Even readings from a meter do not necessarily have a clear meaning.
Having a capacitor in the circuit, such as the body, lets more and more current flow through the circuit, as the frequency gets higher.
Everything has some capacitance. But everything also has some inductance.
This behaves the opposite way. If there is an inductor in the circuit, less and less current can flow through it as the frequency goes up, as we see from:
XL = 2πfL
Here XL refers to the resistance of an inductor, again an impedance. The resistance will be greater as the frequency (f) gets higher and as the inductance (L) gets bigger. To understand inductance we must be aware that every current that flows anywhere creates a magnetic field around itself. That is why a compass needle, held close to a wire with a current flowing in it, will move. Try this with an ordinary small compass. If the wire is straight, the magnetic field around it is not big. But if the wire is in the shape of a coil or spring you can see that the magnetic field going around each wire would add up on the inside where neighboring wires’ fields mesh. So if the current is dc, that is, flowing in one direction only, the field inside could be quite large. If the current is ac the field reverses as often as the frequency of the ac.
Making a magnetic field with a current going through a coil is similar to making a magnet.
There is a North Pole and a South Pole. Every time the voltage reverses, the field has to reverse, too, meaning it must first go to zero (collapse) and then build a new one in the opposite direction.
The faster the frequency, the more work is needed to keep reversing the field. This work can be seen as resistance, explaining why coils do not “like” to let high frequency current pass along them.
To summarize, a high frequency current is “helped” by capacitance but hindered by inductance.
I have not been able to measure the body’s inductance, although there must be some in every conductor just as there is capacitance.
The current going through a capacitor “leads” (gets ahead of the voltage), but through an inductor “lags” (falls behind) the voltage. When inductors and capacitors are connected to each other in various ways, these opposite effects must give some very interesting “waveforms”.
Sometimes the currents might exactly cancel each other, other times adding to each other.
The body as a whole produces waves of energy, whose frequency can be measured. But the waveform has never been seen on an oscilloscope, nor has the frequency been picked up by a probe or frequency counter. If the voltages coming from the body were very small (less than .1 micro volt) a special oscilloscope would be needed.
A dc voltage, when applied to the body does not result in a steady current flow as it would in a conductive material like metal, even though the salt and water compartments of the body are highly conductive. The skin has very high resistance and is therefore the limiting factor in allowing a voltage to induce a current to run through the body. So the greater the area of contact with the skin, the greater will be the current running through the body. For this reason, copper pipes are used as electrodes. When held in the hands, a maximum of contact between skin and electrode can (theoretically) be obtained. Keeping them wet, adding salt, and using a more conductive metal all add slightly but not significantly to the overall conductivity. Applying pressure also adds. That is, they all reduce the resistance of the body “load”, in ohms, as seen by an ohmmeter.
Dc resistance can be measured by an ordinary ohmmeter. To measure the body very good contact must be made to the ohmmeter. Instead of using merely the probes supplied with the instrument, and holding them with the fingers, copper-pipe handholds should be used, attached to the probes with alligator clips. A single layer of wet paper towel should be used to cover the handholds to improve contact further.
After setting the voltmeter to read dc ohms on a range of 10,000 to 100,000, quickly grasp the handholds, noting the first reading. Release hold immediately. Wait for a recovery period of ten minutes or more. Repeat several times, grounding yourself by contacting a water pipe with both hands between measurements. Note that as soon as contact is made the initial reading begins to rise and to continue to rise. Evidently the skin, which is the current limiting component of the circuit, is experiencing some charge separation so resistance goes up and up and therefore less and less current can flow. There may be other explanations, too.
An effect of age can be seen for skin resistance. Children and young persons may have a resistance as low as 10,000 ohms. Older persons may have an initial resistance as high as 30,000 ohms. Measurements made too soon after each other show a tendency to rise, showing that the presumed charge separation does not quickly return.
All these factors make it impossible to simply apply a dc voltage to get a current to flow, which may be a life-saving property in certain circumstances.
To get current to flow in the body, we must take advantage of the capacitors in the body.
Every cell and tissue has capacitance. The membrane of each cell is a layer of fat acting as an insulator between the highly conductive fluid outside (lymph) and the fluid inside the cell. The membrane has capacitance. Only an ac current that moves forward and backward with a high frequency can fill up (charge up) the membrane capacitors and discharge them again, which if done fast enough results in a continuous current flow through the entire circuit.
The amount of charge that can be held in a capacitor will be proportional to the voltage across the conductive areas and to the capacitance of the pair of conductors: Q = CV. Here Q is the charge, C is capacitance and V is voltage.
The voltage felt across the pair of conductors (fluids in this case) will come up to the voltage that is applied to them. Between the conductors a force will be felt, called an electric “field”
affecting anything that is charged. Positively charged entities will be driven to the Negative conductor and vice versa.
How much current will flow “through” the capacitors will be in accordance with Ohm’s law:
E = IR, going up with higher voltage and also going up with higher capacitance or frequency.
When a number of capacitors are all getting their voltage supplied by the same source, they are said to be “in parallel”, like this:
Here represents a voltage source that alternates (ac). The lines are electrical connections. The circles are pairs of conductors like the salt water found inside and just outside each cell or tiny organelle inside a cell. The tapering lines represent a “ground” connection.
For such a parallel circuit where capacitors are each fed independently by the same voltage, they can each charge up to their particular limit. And the total capacitance will be the sum of the individuals, making for a very large capacitance when billions of cells are involved.
CT = C1 + C2 + C3 +...
Here CT the total capacitance, and C1, etc., are individual capacitances.
But when the capacitors are joined to each other a different situation exists. It is called a
“series” arrangement. Any single capacitor in the set can hold only a certain amount of charge (Q=CV); so the smallest capacitor sets
the limit as to how much current can flow through the whole set. It is like a bucket brigade made up of all the townspeople. The smallest child sets the limit on how much water can be passed along.
Remember that current flow is the flow of charge: I = Q/t. Here I is the current in amps, Q is the charge in coulombs, and t is time. Current is the amount of charge flowing past a particular point in the circuit in a given time. So in a circuit where the capacitors are connected to each other in series, the smallest capacitor determines how much current can flow through it. The formula for the total capacitance of a set in series is:
CT =
Various organic capacitors in parallel
Various organic capacitors in series
1 1
C1 + 1 C2 + 1
C3 +…
This shows (after doing some arithmetic) that the total capacitance will be a little less than the smallest capacitor has.
When body cells are connected both in parallel and in series, as they really are, the total capacitance will be limited by the series effect and remain fairly low. But this is a conjecture.
(Remember mine was 135 pF). No similar measurements have been reported to my knowledge.
When a high frequency ac voltage was applied to a human, using hand electrodes, and the current flow measured, it could be seen that the higher the frequency (from zero up), the greater the current. Obviously, the body capacitors were coming into play.
But at about 30,000 cycles per second the current began to decline, showing the resistance was now increasing. The explanations were only speculative: such as “skin effect”, saturation of the capacitors, inductors coming into play, and others.
For this reason a frequency of about 30 KHz (30,000 cycles per second) was chosen for the zapper. But other frequencies may prove to have special value as research progresses.