Silly question about voltage and current

[Farmhand]

Speaking of calculators, I found one that allowed to enter some simple data to calculate the required capacitance to compensate a certain angle of inductive phase lag, but forgot to bookmark it, anyone?

BTW. what are you talking about, a collapsing magnet field does not cause a back emf?? Every cheap voltmeter will proof it does. It takes some time until the current has built up the magnet field. If you disconnect the power source, it will flow back like a rubberband. At least that is what I observed, I have no idea if it contradicts any theories. The voltage is ahead of the current in a coil when you turn it on, that "investment" of energy is the same amount as in the back emf. So no extra energy from the back emf.

I wanna say people should not trust their oscilloscopes too much, but then again, I know that I know nothing.

It depends on what "you're" definition of Back emf is, if you are defining it as returned emf then yes ok, the emf is returned for reuse if the circuit allows it to, but if you're definition of Back emf is the same thing as counter emf then no, the counter emf happens at the same time as the applied emf and the coil discharge happens after, the current is in the same direction and is therefore (forward emf or just emf).

Cheers

[TinselKoala]

DC pulsed into a coil is negative energy,

Uhhhh..... no.

The diode drawing that mentions "negative energy" is also a facepalmer.


Sorry, dude, but you aren't going to be making much progress if you think like that. What is the current flowing through a reverse-biased Zener diode, I wonder, Orange Energy with the pips separated out?

[MileHigh]

Dave, others:

DC pulsed into a coil is negative energy, but the bemf from that coil will be pos.
AC pulsed into a coil is negative on one leg and pos on the other.

There is no such thing as "negative energy" and "positive energy" like you are thinking.  Those comments are ridiculous.

It's the same old cliche.  If you actually understood how a coil works, you would be making some real progress.  But then people get defensive and all pouty when they hear that, or they refuse to even acknowledge the issue.

Some of you build circuits with coils all the time without knowing how they work.  Dave says that he has his "own understanding" but it's clearly the wrong understanding.

As a bare minimum, you should undertake to understand how coils and capacitors actually work, and not how you believe or fantasize how they work.  It's like you are a bunch of people in a wood shop and you don't understand how chisels and files work.

It's really that bad.  What makes it worse is that there are probably 250+ perfectly good clips on YouTube and 1000 web pages were you could learn how these components work.

The rant is over and nothing will change!

MileHigh

[Farmhand]

Yes energy is energy. If we think of it like this - If positive energy does or is work then is negative energy undoing work ? Or is negative energy doing negative work  . Makes no sense.

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[MarkE]

Here is the best that you can do with ideal switches.