It has become clear that if someone of a decent IQ had no idea of electronics, and did not understand the basic idea of DC voltage plus AC voltage existing to a realitive point by post 60, either they are playing games, or need to review elementary education and must realize electronics may not be the field for them. I'm sure there is a ditch that needs digging out somewhere.
It is fun to joke around, but at some point it becomes a waste of time to read.
It is fun to joke around, but at some point it becomes a waste of time to read.
place a stone on a scale, it reads a value. if one pushes down on the stone the value increases, if one pulls up on the stone, the value decreases.
now set the scale to zero with the stone on it, and lift the stone, the scale goes negative. while the stone surely may push down slightly still. (assume the readout moves say a speakercone)
push on it, it goes positive.
now set the scale to zero with the stone on it, and lift the stone, the scale goes negative. while the stone surely may push down slightly still. (assume the readout moves say a speakercone)
push on it, it goes positive.
Actually if you understood superpostion and Fourier series, you would clearly see that there is only one component. If you you really want to dazzle us with your intellect then show how to use Fourier series where a 120 VAC 60 hz current is superimposed on a 300 VAC 90hz current. Oh just to make in interesting make the 120 VAC current 90 deg out of phase in reference to to the 120 VAC. For extra credit superimpose a third component. Ill let you choose the source.
Lets clear things up for the "the degreed electrical engineers".
First I begin with the fundamentals. I will try to do it without quoting any definitions or without misinterpreting theorems or equations. Just the basics.
The basic component in electric current is the electron. Current (electrons) will flow in a conductor when there is a difference in potential. The current (electrons) flow will be from the least potential to the higher potential.
We can show this with a simple experiment.
If we connect a LED to a battery, with the cathode connecting to the negative terminal we will see the LED light. Now if we reverse the LED connection to the battery ( so that the cathode connects to the positive terminal) the LED will not light. Why? First we must understand the potential difference of the battery. The battery is the source of force (emf, you can think of it as a device that creates a potential difference) that allows the electrons to flow. It has a constant potential difference between the negative (lower potential) terminal and the positive (higher potential). As current will always flow from the lower potential to the higher potential one would conclude that the direction of electron flow will always be from the negative terminal to the positive. When we use the LED as conductor between the terminals of the battery, with the cathode connecting to the negative side we see the LED light. The LED lit because current (electrons) are flowing through it. If we reverse the LED connection to the battery the LED remains off as the LED is unable to pass current from the anode to the cathode.
With the example above we have shown that current flows (when using a battery as a source) from the negative terminal to the positive because of a constant difference of potential. We have also demonstrated that an LED will only allow current (electrons) to flow through it in one direction.
Lets now remove the battery and replace it with a step down transformer to convert our house current to something our LED can take. We will leave it a 60Hz. If we connect our LED cathode to one of the output leads of the transformer and connect the anode side to the other lead the LED will lite. To the an observer the LED will appear to a be a constant light. If we reverse the LEDs connection to the transformers output leads the LED lite. Just like before the light will appear to observer to be a constant light. Why did the LED lite when connected both ways? Without getting in to the details of how a rotating magnetic field displaces electrons in a coiled conductor ( I'll leave that to the reader. Pick your own source) we simple need to understand that the source is changing its polarity at a regular period of time. This constant change in potential causes the electrons to flow in one direction then the other. Lets remember that current (electrons) will always flow when there is a difference in potential. The direction of the electrons will flow is from the a lower potential to a higher potential. Now that we understand that the source in this example is periodically changing its polarity ( there by changing the direction of electron flow) we can understand why the LED lites irregardless of how its connected to the source. I stated that to the observer it would appear that the light is constant but I will show later that it actual turns on and off.
Up to this point I have not defined anything. I have simply shown that current (current) flows differently in relation to its source.
Now lets add a potentiometer before the LED in our example battery circuit described earlier. Lets assume the LEDs cathode is placed to the negative side of the circuit. As we repeatedly adjust the 'pot' up and down, the observer will witness that the LED will repeatedly brighten and dim. Why. Repeatedly adjusting the potentiometer up and down, has the affect of increasing and decreasing the current (electrons) flow to LED. As the current increases ( increasing the number of electrons flowing) the LED will brighten. As the current decreases ( decreasing the number of electrons flowing) the LED will dim.
Now reverse the LED in the above example so that the cathode is towards the positive terminal. If we repeatedly adjust the 'pot' up and down the observer will witness no change to the LED. It ramains off. why? Current (electrons) flows from a lower potential to a higher potential, as there is no potential change in reference to the source, and LEDs only allowing current (electrons) to flow in one direction no current can flow through the LED.
Notice in the first example (the LED brightened and dimmed in relation to the adjustment of the 'pot') that if we were to plot the increase and decrease of current (electrons) through the LED on a graph, we would see a sine wave. It also show that current (electrons) flowing in one direction can have fluctuating amount of current.
Lets consider the "house current" example earlier. Lets say that its output is 3 VAC at 1Hz. We have shown that the source is regularly changing its polarity. The rate of change is the "1Hz" part. Image if the current (electrons) flows in one direction for a half a second and the other direction for half a second. What would the observer see the LED do? It would 'flicker' on and off. Why? The LED will only allow the the current (electron) flow through it in one direction. When the polarity (potential difference) of the source is such that the current (electrons) are flowing from from the cathode to the anode the diode lits. When the polarity changes, current will flow in the other direction. The LED will only allow current (electrons) to flow through it in one direction, the change in direction of flow cannot flow through the LED and the LED become unlit. Its important to remember that we can still reverse the LEDs connection to the transformer and it will still 'flicker'. Notice that the LED has taken a source of current that periodically changes its electron flow direction, and is passing only electrons in one direction from it.
At this point some are going nuts! It would be something like "but the house current example the voltage goes negative". lets clear that up, and we can use superpostion to do it.
If we looked at the voltage over time in the last example we would see the voltage goes from +3 volts to -3 volts at the LED. We can change this so that the voltage at the LED would remain positive. We can change it so that the voltage over time changes from +9 volts to +3 volts at the LED. If we take a 6 volt battery and connect to the circuit so that the negative (lower potential) terminal connects to the cathode side of the LED and the positive (higher potential) connects to the anode side.
When the current (electrons) from the transformer source flow in the same direction as the connected batterys current (from the cathode to the anode of the LED) the current is total or sum of the batteries current (electrons) and the transformers current (electrons). It is important to understand that the transformers electrons are no different then the batteries electrons. It is just a total of the combined electrons. When the transformers polarity changes its current changes direction. The battery now has a potential difference with the transformer and its positive terminal on the other side of the LED. This potential difference will cause some of the electrons to flow to the transformer and some to flow through LED to the positive terminal. The amount of electrons flowing through the LED is the amount of potential difference between the transformer and the batteries positive terminal in relation to the negative terminal of the battery. You need to realize that the electrons flowing through the LED are always traveling in the same direction and that those electrons are increasing and decreasing in the amount of electrons flowing. To an observer, the LED would repeatedly brighten then dim.
Now we can clarify things for the quoted poster.
Superpostion theorem is used to analyze circuits containing multiple types of applied sources. Like the one a at the top of this post. In no way does it prove or disproves the direction of current flow in a single source.
A Fourier series is used to mathematical separate complex wave forms into there individual components. In your example of the half wave rectifier there was only one source (component) applied to the rectifier. The AC component. If we apply another source (component) to your rectifier example say DC (component), then we would have a DC component and an AC component to separate out using Fouriers
If you really understood how to apply a Fourier series you wouldn't have misquoted what the actual components are. E/pi*1 is a reference point and not a DC component in the rectifier example you used. Again just to clear, To separate a DC component from the rectifier example, we we need to apply a DC component (source) as if demonstrated above.
Conclusion:
In some circuits, current (electrons) flow only in one direction. They do so because polarity (potential difference) relative to its source never changes. An example is a battery. A sine wave can be induced into current (electrons) flowing in one direction by the use of a device such as a potentiometer.
In other circuits current (electrons) flow in one direction for a period of time then reverse and travel in the opposite direction for a period of time, relative to its source. An example would be the current in your home. Unlike sources with a constant polarity, these sources produce a natural sine wave because of the constantly reversal of polarity.
Have you really that much time to waste ?
Just for fun: how do you call V(n003), the green trace ? It's taken at the right of the led, atop of R1.
V1 is a pure AC source of 2Vp-p, V2 is a 5V battery.
You have the exact same sine atop of V1 and R3 btw... (red trace)
Just for fun: how do you call V(n003), the green trace ? It's taken at the right of the led, atop of R1.
V1 is a pure AC source of 2Vp-p, V2 is a 5V battery.
You have the exact same sine atop of V1 and R3 btw... (red trace)
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One of the reasons I like alternating current is because it's much more politically correct than direct current. It's very green.
Electrons in direct current run through their conductors like lemmings over a cliff never to be seen again - what a waste!
Electrons in alternating current can be captured for all time providing you make their conductor just longer than the distance they can travel in half of their cycle.Thus they can be re-used over and over again - now that's my kind of recycling..
And remember folks , dc electrons are here today gone tomorrow strangers
but ac electrons are yours for life - not just for Xmas
Hicc.....
Electrons in direct current run through their conductors like lemmings over a cliff never to be seen again - what a waste!
Electrons in alternating current can be captured for all time providing you make their conductor just longer than the distance they can travel in half of their cycle.Thus they can be re-used over and over again - now that's my kind of recycling..
And remember folks , dc electrons are here today gone tomorrow strangers
but ac electrons are yours for life - not just for Xmas
Hicc.....
One of the reasons I like alternating current is because it's much more politically correct than direct current. It's very green.
Electrons in direct current run through their conductors like lemmings over a cliff never to be seen again - what a waste!
Electrons in alternating current can be captured for all time providing you make their conductor just longer than the distance they can travel in half of their cycle.Thus they can be re-used over and over again - now that's my kind of recycling..
And remember folks , dc electrons are here today gone tomorrow strangers
but ac electrons are yours for life - not just for Xmas
Hicc.....
Hmmm... So, why should I pay to PG&E for electrons that never escape their premises, if they supply real AC?
How far DO those little electrons go in a half cycle anyway? How long would the wire need to be? If you put DC electrons in a wire at one end, do the "same" electrons appear at the other end at the load terminal? How do electrons travel through a wire? Electrons have mass. Is there any mass transfer associated with electrical current? How do we know that electrons "flow"? Are we trapped in an analogy with no way out?
I'm reminded of the first time I looked out over a classroom filled with college freshmen, teaching basic electricity and electronics, and the first question from one very bright student was in effect "so, Mr. Koster... how DO those electrons get from one end of a wire to the other anyway?" The analogy wasn't holding water for him ;-)
I'm reminded of the first time I looked out over a classroom filled with college freshmen, teaching basic electricity and electronics, and the first question from one very bright student was in effect "so, Mr. Koster... how DO those electrons get from one end of a wire to the other anyway?" The analogy wasn't holding water for him ;-)
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"Assuming a current I=3 amperes, and a wire of 1 mm diameter (radius in meters = 0.0005m). This wire has a cross section area of 7.85×10-7' m2 ('A= π 0.00052 ). The charge of 1 electron is q=1.6×10−19 Columbs. The drift velocity therefore can be calculated:
V= I/nAq V = 3 / (8.5×1028 x 7.85×10-7 x 1.6×10−19 ) V = 0.00028 m/s"
[V] = [Amps] / [electron/m3] x [m2] x [Columbs/electron] = [columbs] / [seconds] x [electron/m3] x [m2] x [Columbs/electron] = [meters] / [second]
from WIKI; drift velocity, Drift velocity - Wikipedia, the free encyclopedia
astonishingly little eh?
in a vacuum tube with say 300V between cathode and anode the final velocity is about 0,03 C
or 10000 km/s
V= I/nAq V = 3 / (8.5×1028 x 7.85×10-7 x 1.6×10−19 ) V = 0.00028 m/s"
[V] = [Amps] / [electron/m3] x [m2] x [Columbs/electron] = [columbs] / [seconds] x [electron/m3] x [m2] x [Columbs/electron] = [meters] / [second]
from WIKI; drift velocity, Drift velocity - Wikipedia, the free encyclopedia
astonishingly little eh?
in a vacuum tube with say 300V between cathode and anode the final velocity is about 0,03 C
or 10000 km/s
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"The charge of one electron might be used as a unit of electrical charge, since charges are created by displacement of electrons; but the charge of one electron is so small that it is impractical to use. The practical unit adopted for measuring charges is the COULOMB, named after the scientist Charles Coulomb. One coulomb is equal to the charge of 6,280,000,000,000,000,000 (six quintillion two hundred and eighty quadrillion) or (6.28 x 10-18) electrons. When a charge of one coulomb exists between two bodies, one unit of electrical potential energy exists, which is called the difference of potential between the two bodies. This is referred to as ELECTROMOTIVE FORCE, or VOLTAGE, and the unit of measure is the VOLT.
*** Electrical charges are created by the displacement of electrons, so that there exists an excess of electrons at one point, and a deficiency at another point. Consequently, a charge must always have either a negative or positive polarity. A body with an excess of electrons is considered to be negative, whereas a body with a deficiency of electrons is positive." NEETS Module 1
"Alternating current is current which constantly changes in amplitude, and which reverses direction at regular intervals. You learned previously that direct current flows only in one direction, and that the amplitude of current is determined by the number of electrons flowing past a point in a circuit in one second. If, for example, a coulomb of electrons moves past a point in a wire in one second and all of the electrons are moving in the same direction, the amplitude of direct current in the wire is one ampere. Similarly, if half a coulomb of electrons moves in one direction past a point in the wire in half a second, then reverses direction and moves past the same point in the opposite direction during the next half-second, a total of one coulomb of electrons passes the point in one second. The amplitude of the alternating current is one ampere." NEETS Module 2
I have continually provided my source of information (The NEETS Modules) . I repeatedly posted multiple sources that reinforce the information in it. In 16 page of posts not one person has provided proof that the definition of AC and DC are wrong. A persons opinion, or interpretation does not constitute proof.
If I am confused and misinterpreting things, then explain in simple terms what I am getting wrong. Provide proof. There should a variety of sources that back your explanation. I am more then willing to accept that I or the NEETS modules are wrong. But a I am not going to take your word for it. If you have been reading through the multitude of conflicting post in this thread would you?
You do realize that the NEETS serie is aimed at a basic understanding of electricity notions for technicians ?
At this point, you're just splitting hairs about a simplified definition. All the electrical engineers I know (and having a brother and a cousin holding their degree in such field, I've been in contact with quite a few) will speak of AC as soon as they're faced with current flowing in a sinusoidal pattern, whether or not it's actually reverting direction (which happens as soon as the AC current is mixed with DC).
Oh, and by the way, there aren't many conflicting posts in this thread. They all try to say the same thing: as soon as DC voltage is surimposed on AC voltage (or the other way around), you get a composite signal, with a DC and AC components. Noone bothers to call that "fluctuating DC" but you.
At this point, you're just splitting hairs about a simplified definition. All the electrical engineers I know (and having a brother and a cousin holding their degree in such field, I've been in contact with quite a few) will speak of AC as soon as they're faced with current flowing in a sinusoidal pattern, whether or not it's actually reverting direction (which happens as soon as the AC current is mixed with DC).
Oh, and by the way, there aren't many conflicting posts in this thread. They all try to say the same thing: as soon as DC voltage is surimposed on AC voltage (or the other way around), you get a composite signal, with a DC and AC components. Noone bothers to call that "fluctuating DC" but you.
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