MH's ideal coil and voltage question

[partzman]

When 4 volts is applied to a 5H inductor, current will rise at .8 amps per second.  But why does that happen?  Why does current only rise at .8 amps per second?  What is regulating or limiting the current's rate of change so that current does not increase at a faster or slower rate?

Consider this:

EMF=dI*L/dt tells us WHAT happens.  CEMF=dI*L/dt tells us WHY it happens. 

PW

I assume you have a typo above since by definition, Cemf = -dI*L/dt.

We have a stalemate here between me, yourself, Poynt, and others because at present, I have seen no physical or mathematical evidence to convince me otherwise including your explanation above. I guess that is my problem!

So, in order to not be a burden, I will no longer post on the subject unless I can prove my point at least mathematically.

pm

[picowatt]

I assume you have a typo above since by definition, Cemf = -dI*L/dt.

We have a stalemate here between me, yourself, Poynt, and others because at present, I have seen no physical or mathematical evidence to convince me otherwise including your explanation above. I guess that is my problem!

So, in order to not be a burden, I will no longer post on the subject unless I can prove my point at least mathematically.

pm

Consider two voltage sources connected in parallel.  One Vsource represents the applied EMF, the other Vsource represents the inductor's generated CEMF.  The first Vsource, representing EMF, is set to output +4 volts.

What voltage must the second Vsource be set to output in order for their to be no current flow?

PW

[tinman]

I see RPM as the voltage and torque as the current. The governor I would be referring to (more or less equal to the inductor current limiting process) would limit torque not voltage. So it would be like an centrifugal clutch that could adjust itself to produce a constant rise in torque.

OK,i think you had better leave out trying to link this to engine RPM and torque,as none of that makes sense. A centrifugal clutch can only deliver the same amount of torque as the engine,and that torque is determined by the RPM torque range of the engine,where the RPM is limited by the governor. This is the very same as the voltage being able to increase or decrease the amount of current that flows over time,where the system has resistance.

There is no loss; cemf=Vin at all times with the ideal inductor

.

OK,this is where i do not understand.
If there is no loss !somewhere! ,then how dose current flow if we have equal and opposite?

For a non-ideal inductor, that is correct. At the instant Vin is connected, unless R is large relative to the L value, the resistor will have very little voltage across it compared to the inductance. So for normal non-ideal inductors, this holds true. You can confirm this on your bench to a certain degree. Obviously real inductors already have a series resistance, but you will have to introduce another so you can measure the voltages across each when the connection is made.

Very little is enough for a potential difference,and there for,enough for current to start to flow.
I tried a few inductors tonight,and in each case,i got a 600mV difference between the EMF and CEMF values--see scope shot below of 500mH inductor.
The yellow trace is the EMF,and the blue trace is across the inductor.
The winding resistance value is 1.2 ohms.

Asking this question indicates that you do not understand the explanation.

No i dont.
If the negative feed back value is equal to that induced,then why would there be a net current flow in one direction?
Im seeing this as an AC type deal,where the reverse current value is the same as the forward current value--as there are no losses.


Brad

[tinman]

Consider two voltage sources connected in parallel.  One Vsource represents the applied EMF, the other Vsource represents the inductor's generated CEMF.  The first Vsource, representing EMF, is set to output +4 volts.

What voltage must the second Vsource be set to output in order for their to be no current flow?

PW

+4 volts

Brad

[3Kelvin]

I think, there is a request to explain the the asymmetry of V.. Source and V ... Induced. If there is Vs=Vi ,it seem to be no asymmetry. 

But whats about the payload for Vi ?
Vi can only exist due to the changing magnetic field, for that we need current that changes every time unit.

so what is the result ?

Love + Peace
3K