My Friends,
This thread is to clear up a debate on Polarity of a Generated E.M.F.
Over the years, I have seen some Researchers confused with the Polarity of the E.M.F Generated. Some Researchers try to tell you that the Magnetic Fields are Aiding each Other, when the truth is, that's totally Wrong! Its very important, that we get this right in our minds, because becoming confused over such a simple thing is definitely the difference between Success and Failure! Perhaps some use this as a new Tactic, to try to confuse others, and thus stop Progress in the Community? I don't know.
I honestly thought the Community was a lot further ahead and understood this in much better detail than we see sometimes. I have covered much of this many times in different places here on this forum!
Those before us and Electromagnetic Induction
It is very important that you know Electromagnetic Induction in Detail! Floyd Sweet and many others had an excellent background and knowledge of Electromagnetic Induction. For example, one of the greats, Clemente Figuera said:
PRINCIPLE OF THE INVENTION - Watching closely what happens in a Dynamo in motion, is that the turns of the induced circuit approaches and moves away from the magnetic centers of the inductor magnet or electromagnets, and those turns, while spinning, go through sections of the magnetic field of different power, because, while this has its maximum attraction in the center of the core of each electromagnet, this action will weaken as the induced is separated from the center of the electromagnet, to increase again, when the induced is approaching the center of another electromagnet with opposite sign to the first one.
Because we all know that the effects that are manifested when a closed circuit approaches and moves away from a magnetic center are the same as when, this circuit being still and motionless, the magnetic field is increased and reduced in intensity; since any variation , occurring in the flow traversing a circuit is producing electrical induced current .It was considered the possibility of building a machine that would work, not in the principle of movement, as do the current dynamos, but using the principle of increase and decrease, this is the variation of the power of the magnetic field, or the electrical current which produces it.
The voltage from the total current of the current dynamos is the sum of partial induced currents born in each one of the turns of the induced. Therefore it matters little to these induced currents if they were obtained by the turning of the induced, or by the variation of the magnetic flux that runs through them; but in the first case, a greater source of mechanical work than obtained electricity is required, and in the second case, the force necessary to achieve the variation of flux is so insignificant that it can be derived without any inconvenience, from the one supplied by the machine. Until the present no machine based on this principle has been applied yet to the production of large electrical currents, and which among other advantages, has suppressed any necessity for motion and therefore the force needed to produce it.
Floyd Sweet mentions Faradays Law about five times in his writings!
Plain and simple, all of these people before us, had an excellent knowledge of Electromagnetic Induction, remembering it was big in those days, it was all the rage, as we were having patent after patent being issued for all sorts of Electromagnetic Inventions. Inventions we all take for granted today!
The E.M.F Generated, in Units of Volts, or some say a Voltage, is always the result of Faradays Law and Lenz's Law combined, thus we get:
E.M.FVolts = -N δΦB / δt
Where:
- E.M.F is the Potential Charge Difference in units of Volts.
- The Negative Sign ( - ) represents Lenz's Law and shows the Bucking Nature of the E.M.F.
- Delta ( δ ) is the Change: Max - Min = Delta, the total Change.
- Phi ( Φ ) is the Magnetic Field Density B, the Window of total Magnetic Flux.
- Time t is the total Time Difference. End time - Start Time in seconds.
This Image is one of the best I have found to explain the Lenz's Law Negative Sign
Electromagnetic Induction in a Transformer
In an AC Voltage Source, supplying an AC Voltage across an Input Coil, we have four phases or Quadrants we must consider, however, we only have two Phases in the AC Source.
From a net Zero Field, there is only ever two situations that a Coil is going to experience.
- A North Pole changing in Magnitude from BMin to BMax and then back to BMin again.
- A South Pole changing in Magnitude from BMin to BMax and then back to BMin again.
This Change in Magnetic Field B, from BMin to BMax and then back to BMin again, constitutes one Half Cycle, a DC Half Cycle:
It does not take much to see, that the Two situations above, gives us Four Quadrants we need to think about:
Where:
- The Red Electric represents the Coil being supplied with a Current until the Magnetic Field builds to BMax, from BMin.
- The Green Magnetic represents the Coil suppling a Current until the Magnetic Field moves from BMax, to BMin.
NOTE: For this Half Wave DC Cycle, a Diode does NOT change Polarity during this portion of the Cycle, its a specific Polarity and the Diode will only ever conduct in One Polarity for this specific Half Wave!
Also NOTE: The Red Electric Portion is always in a Bucking Form between Primary and Secondary Coils! Always and there is nothing you can do to change this! This Opposition is why the Magnet falls so slowly:
Magnetic Field Opposition
Bucking Magnetic Fields are the norm! We see every time we Generate an E.M.F, we see the Secondary Coil Oppose the Primary Coil! There is, again, two Phases for each Half Cycle, a Magnetisation Phase, and a Demagnetisation Phase.
The following Simulations are from the MIT Courseware, in Electrodynamics. It is very easy to prove this sim correct on the bench!
Primary is on the Bottom Coil, Secondary is on the Top Coil, thus the Conventional Transformer Modeling Standard.
The Magnetisation Phase:
The De-Magnetisation Phase:
Please Note: Every single Coil starts off with a Magnetic Field at Earths Magnetic Field Density, sometimes very small, about 0.5 of a Gauss. So there is no Negative, or a net Equilibrium value of around 0.5 Gauss.
Always the Currents flow in Opposite Directions and always the Voltages are Generated in the Negative of the Source, in a Bucking Nature.
Current Flow
We have two Rules to work out what the Current Flow will be, because in the old days, we assumed Current flowed from Positive to Negative, however, as time went on, we realised we had it wrong, and we corrected the Rules, and swapped hands.
We used to use what's called the Right Hand Grip Rule:
Ref: Transformer Phasing - The Dot Notation
You can see, we have Magnetic Field Opposition occurring here, in a Transformer.
Today we know we have a Current Flow from Negative to Positive, so working out how a Current Flows now requires the Left Hand Grip Rule, using the Left Hand you can grip the Coil and
I use Conventional Current, because everyone knows what it is, and some dorks try to catch me out and try to correct me, which is petty and pathetic, because they should know already, I am referring to Conventional Current. However, the same idea applies, take note of the Voltage Polarity and apply what rule you want, to work out which way the current will flow.
NOTE: A Generated Voltage is in the opposite direction compared to an applied Voltage, so please remember this!
Exceptions
In a Non-Standard situation, we can see what appears to be Exceptions to the above situation. The Mr Preva Experiment does appear as an Exception, but you must remember, once understood, it does follow this standard! This is because, at Resonance, the Coils do actually Generate more E.M.F and thus the Current flows as a result of the Generated E.M.F.
Making proper and accurate observations as to what the Source of the Generated E.M.F is is important and if you want to be taken seriously, a must!
We are dealing with Coils that have a difference in Polarity, and an E.M.F is Generated on all Coils, but the Source of the E.M.F is the key to understanding the Machine! Electromagnetic Induction can and does occur in more than one direction in the same machine! Many will not like that statement, but it is true!
Best Wishes,
Chris
