Electrical / Electronic Theory and Learning Center > Induction
Induction: methods and madness
Grumpy:
We are all familair with the term "induction" and Faraday's experiments that linked magnetic fields with electric fields.
"Electromagnetic induction is the production of voltage across a conductor moving through a magnetic field."
If we are to find another means of inducing current, one perhaps better than the oens we currently use, then we need to know "why" a moving, or changing magnetic field casues electrons to flow in a conductor. What is really going on when we move a magnet past a wire? We all know it works, but "why" does it work?
This is one of the basic questions I asked years ago when I first ventured onto Eskimo.com. When you ask these basic but difficult to answer questions, do not be surprised at the answers you find.
The other side of this question is: "Why" does electric current produce a magnetic field?
(The answer: "It just does" is no longer satisfactory.)
EDIT:
SM stated toward the end of the UEC video that the TPU utilizes another form of induction, another way to make electrons flow to produce electrical current.
What was he talking about?
Peterae:
--- Quote ---( The "reversed form" (negative solution) of Maxwell's Fourth Equation, states that a magnetic field can be produced without current flowing in a wire. — TRC — )
--- End quote ---
Cross field antenna
BEP:
The problem we face with normal induction being a retarding effect is Lenz.
Lenz is my favorite as it does appear to have a hole in the law. This is a prime example of the math being correct but the model being incomplete.
CFAs are very real and seem to use this hole but none I've looked into could be considered OU.
Do two simple things to understand this hole.
1. Look at the actual and empiric magnetic polarization of a simple multiturn loop/pancake coil with ONE LAYER of turns. Use as many turns as possible to see the effect best. DON'T assume you know OR assume the book is correct!
2. The rules are a current is induced into that loop when a magnet approaches. This current direction generates a magnetic field opposing the one approaching.
See, for yourself, how this doesn't work unless you have two exactly equal and opposing fields approaching the opposite ends of the coil's central axis. Then think about what happens to these two approaching and opposing fields.
Maybe it would be eaisier to clap your hands with a grape between them?
Currently, we just say induction doesn't work with these angles.
The correct statement is 'Induction always works if you have and understand a completed Lenz law/Faraday Law of Induction'.
If you look at all this and see nothing interesting. I am sorry. Maxwell inversions explain it. Van der Pol, without modern adjustments to insert COE explains it.
It is still induction. It just isn't as 2D as folks think.
Grumpy:
How does a "magnetic field", in motion or changing, cause electrons to flow? The amgnetic field is able to imaprt motion to physical objects (electrons), but only if it is moving or changing. Yet, when I place a magnet near an iron object, the object is pulled toward the magnet. If I use a compass, the new vector torward the magnet is held until the magnetic field changes, and it was the movement of the magnet to a location near the compass that caused the compass needle vector to change.
What aspect of a "magnetic field" allows it to act on objects this way?
Do opposite poles induce current in opposite directions?
BEP:
If you try my magnet dropping experiment you may be on your way to a more correct question and then an answer, maybe.
I haven't made it all the way yet.
--- Quote ---Do opposite poles induce current in opposite directions?
--- End quote ---
I misread or was just in a hurry for work...
Approaching opposing poles induce a radial current.
Yes, of course. Given all other parameters are the same. South or North poles with the same movement relative to the wire induce opposite currents.
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