MrAl,
I think you are making your remarks to me. I always try to name the person to whom I am talking.
I see no dichotomy in what I said with regard to voltage control causing current (notice I said just "current", not "current flow"). You have to distinguish between control causation (voltage) and consequence (current). Just because current is a consequence of voltage does not mean that current is controlling something.
And so what if there is both voltage and current in a device that can be plotted. I said before that you cannot determine what is controlling a device by graphs, equations, or measurments. You have to know the physics of the device to find out that information. For semiconductors, the physics point to the energy concentration per unit charge (voltage=joules/coulomb) that controls the device.
Ratch
<still editing for format>
Hello again,
"I see no dichotomy in what I said with regard to voltage control causing current (notice I said just "current", not "current flow").
You have to distinguish between control causation (voltage) and consequence (current). Just because current is a consequence of voltage
does not mean that current is controlling something."
That's an interesting statement. You are stating the current is a consequence of voltage, but that's only true in a separate circuit
apart from the 'voltage'. Since that's not always the case, and when we want to know how a device is 'operated', we want to talk about
the voltage and current in the SAME circuit. Let me try to make this a little more clear.
When we energize say a gate, we are trying to control the transistor. Once we establish a voltage, we see drain source current flow.
But the whole idea behind control is what are the signals that we are applying TO THE CONTROL terminal to get that control, not just
some random signals that exist in other places in the device.
So the whole point is what is going on with the control signal itself. And in order to drive the device we have to apply both current
and voltage, because here is no way to apply a voltage from out of nowhere to a device.
"And so what if there is both voltage and current in a device that can be plotted. I said before that you cannot determine what is
controlling a device by graphs, equations, or measurments. You have to know the physics of the device to find out that information. For
semiconductors, the physics point to the energy concentration per unit charge (voltage=joules/coulomb) that controls the device."
I did not create the graph and then looked at the physics, i looked at the physics first and then came up with the graph. That graph
shows how EVERY device behaves with respect to current and voltage, even if you could somehow prove that a device could be totally
voltage controlled (pure voltage control is shown along the x axis). Trying to void that graph is the same as voiding your own
statement that something can be purely voltage controlled because pure voltage control appears along the x axis. You're also trying to
void many devices that exists because that graph represents all devices that are voltage or current controlled (if they could exist
alone) and anything in between (except negative polarity signals were left out for simpliciy).
You're also now stating that it is in fact the energy that makes the difference, but still claiming that voltage is the controller and
even typed out a little formula for the voltage to emphasize this
The circuit you seem to be working with is a totally fictious circuit in every sense of the word. You've somehow managed to get a
voltage to appear somewhere you wanted it to be without moving any charge. I'd like to see how you did this
This is why the transistor is sometimes also quoted as being "Charge Controlled". In this scenario the movement of charges controls
the device. But we all know you cant move a charge without energy, and energy cant come from voltage or current alone but requires
both.
So back to your statement, "current is a consequence of voltage". Since the movement of charge is the only way to establish a voltage
in the same circuit loop, any voltage that we apply has to come through wires and so there has to be movement of charge just to get
that voltage there, which means charge has to move though the wires as the voltage is climbing.
So when we try to get to the "underlying physics", we would like to know the most basic physical principles at work, not some super
shelf where it looks like something else is happening.