Help understanding back emf I'm trying to understand back emf & self inductance. This is what I know: let's say that you have a current around a loop. I picture this as a vector going around the loop. Then we decrease the current by a small amount, which equates to imagining a smaller vector pointing in the opposite direction. Lenz's Law tells me that emf is in such a direction as to oppose any change in current. Therefore, emf must be in the original current's direction.
Questions:


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*First of all, is my understanding correct?

*Should I think of emf as a vector, i.e. as something with a magnitude and a direction? I ask because my book always talks about its direction.

*What are the physical objects that actually create emf? Whenever I imagine a current, I imagine electrons moving through a wire. If this is correct, then what moves through the wire when there is back emf? Electrons?
 A: It's a reaction that the circuit gives for changing voltage or magnetic field. Its logic is like this:


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*First you have a circuit without voltage let's say.

*When you start to increase the voltage, circuit wants to keep its original state which was when there was no voltage.

*Because of that circuit then creates voltage which would decrease the increase in voltage.


It's basically the circuit's way of protecting itself against voltage changes.
In case of a Magnetic field, the logic is same. When you increase the magnetic field around the bobin it creates a voltage opposite direction of the increasing magnetic field so it protects itself.
When high voltage or magnetic field decreases circuit supports the voltage so it can keep the same voltage around itself. Again the logic is to keep the state stable.


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*(-) in the Lenz Equation means that what you do to the circuit it will always act against it. You shouldn't think emf as vector it's scalar as far as i know but its reasons are vectoral just something to keep in mind.

