Joule Thief 101

[tinman]

OK MH

I ask this question of all the EE guys here.

Can a voltage of 4 volts exist across an ideal inductor,(where an ideal inductor has a resistance value of 0 ohms), for 3 seconds as stated in MHs question?.

Poynt,PW,Verpies-ETC ?


Brad

[tinman]

https://en.wikipedia.org/wiki/Inductor
An "ideal inductor" has inductance, but no resistance or capacitance

http://www.electronics-tutorials.ws/inductor/inductor.html
An ideal inductor has no resistance only inductance so R = 0 Ω's

http://www.rfcafe.com/references/electrical/inductance.htm
An ideal inductor is the equivalent of a short circuit (0 ohms)


And this one MH,that might show you that your answer was not only incorrect,but your question was not possible -as i had already stated.
it is not possible to hook up an ideal inductor to an ideal voltage source,

Reference https://www.physicsforums.com/threads/inductor-in-dc.205550/
It is not possible to hook up an ideal inductor to an ideal voltage source,


Brad

[tinman]

Quote

You have an ideal voltage source and an ideal coil of 5 Henrys.  At time t=0 seconds the coil connects to the ideal voltage source. For three seconds the voltage is 4 volts.  Then for the next two seconds the voltage is zero volts. Then for two seconds the voltage is negative three volts, and then for the next six seconds the voltage is 0.5 volts.  Then after that the voltage is zero volts.

The correct answer for this question is--you cannot place an ideal voltage across an ideal inductor-or coil,as the chosen term from MH.

MHs results from his modified test parameters

The current through the ideal coil starts from zero at time t = 0 and then increases with this formula:  i = 1.33*t^3.

Time..........Voltage.........Current
0...............0.................0
1...............20...............1.33
5...............500.............166.67
10.............2000............1333.33
20.............8000............10666.67
50.............50000..........166666.7

The quoted results above are also incorrect, as T=L/R,and where R=o in an ideal inductor,and thus were T becomes instantaneous,and I becomes infinite.


Brad

[wattsup]

Again,your question-->
You have an ideal voltage source and an ideal coil of 5 Henrys.  At time t=0 seconds the coil connects to the ideal voltage source. For three seconds the voltage is 4 volts.  Then for the next two seconds the voltage is zero volts. Then for two seconds the voltage is negative three volts, and then for the next six seconds the voltage is 0.5 volts.  Then after that the voltage is zero volts.

@tinman

Is this the question that I could not answer? I am confused as usual on this thread. Stuff gets thrown around so fast.

If a voltage source changes in time, why is it ideal? Ideal means the voltage stays the same across the connections of the coil regardless of how the coil handles it. There is more but no need to go any further.

wattsup

[tinman]

@tinman

Is this the question that I could not answer? I am confused as usual on this thread. Stuff gets thrown around so fast.

If a voltage source changes in time, why is it ideal? Ideal means the voltage stays the same across the connections of the coil regardless of how the coil handles it. There is more but no need to go any further.

wattsup

Yes Wattsup.
This is the question that MH asked you and EMJ to answer.
MH answered the question(after a modification to the question),and got it wrong.

So feel easy Wattsup,as it was a question MH him self could not answer correctly,and all the bad karma he threw your way,and the gloating he made throughout many threads regarding this question,simply can now be dismissed as garbage.

As i stated,and provided links to the same,an ideal voltage cannot be placed across an ideal coil.
As an ideal coil/inductor has a resistance value of 0,and where an ideal voltage is placed across that coil/inductor,the current rises to infinity. And as T=L/R,and where R=0 in an ideal coil/inductor,then T is instantaneous.So you dont have to worry about the voltage changing over time,as the time is instant. There is also the fact that MHs question states 4 volts for 3 seconds over an inductor(ideal inductor)that has a resistance of 0 ohms.
So now we have an infinite source of power

What happens when you have an infinite source of power?
What happens when an unstoppable force meets an unmovable object?.


Brad