When an inductor discharges it can obtain voltages much higher then the source. I know this has to do with an inductor's opposition to current change, but I don't understand why and my book is doing a really poor job of making it clear.
The fact that the twelve volt battery in a car produces 25kV is amazing, but I just can't grasp the whys and hows..
Thanks Alot for any aid!
Frank.
In most cases the current is turned off imediately so this fact is not taken into account when determining the high voltage produced by an inductor.The faster you open the higher the voltage.. but the current is minuscule...
The magnetic lines (flux) cut all the turns of the primary when the flux is expanding and this produces a voltage in each turn, in the opposite direction, that can be as much as 99% of the energising voltage. Thus the resulting voltage seen by the inductor can be very small and thus a very small current flows.And from what Colin was saying, it sounds like the magnetic flux lines "cut" the coil in such a way that it interrupts the current as to cause it to reverse, caused by the inductor's protective voltage.
You're misunderstanding something, because the current doesn't change direction. The reverse voltage is what's required to keep the current moving in the forward direction in the coil once the supply is removed. If you apply a diode to in reverse across the coil you'll see at switch off time that the current is still flowing around the coil in the same direction and will continue to flow dissipating as heat as the magnetic coils energy is turned back into an electric field. The reverse voltage is the magnetic field building energy up, it would cause current to flow in the opposite direction in the circuit it's attached to, NOT itself. Basically once that energy is removed from the circuit, that energy has to go somewhere so it'll find it's most direct route to gruond generating as much voltage as required to get there.And from what Colin was saying, it sounds like the magnetic flux lines "cut" the coil in such a way that it interrupts the current as to cause it to reverse, caused by the inductor's protective voltage.
. There are so many mistakes in this reasong that it should be removed from the posting. Your reasoning is totally INACCURATE.The reverse voltage is what's required to keep the current moving in the forward direction in the coil once the supply is removed.
The voltage generated is a characteristic of the inductor - the amount and quality of the magnetic circuit, the number of turns, and the amount of energy in the inductor, in the form of magnetic flux. "As much voltage will be generated to get there" is totally inaccurate. The voltage may be very high or it may be quite low. It's like saying: "the money that will be despoted into my account will be sufficient for anything I want to buy this week!!!! How do the depositors know how much money I need this week???Basically once that energy is removed from the circuit, that energy has to go somewhere so it'll find it's most direct route to gruond generating as much voltage as required to get there.
He came up with that because that is what happens. The initial reverse voltage will indeed go to whatever is required to keep the inductor current flowing when the charging voltage is removed.How on earth did you come up with this: The reverse voltage is what's required to keep the current moving in the forward direction in the coil once the supply is removed.
How can you have voltage flowing in one direction and current flowing in the reverse direction, AT THE SAME TIME?????The initial reverse voltage will indeed go to whatever is required to keep the inductor current flowing when the charging voltage is removed.
How can you have voltage flowing in one direction and current flowing in the reverse direction, AT THE SAME TIME?????
Would you be able to tell me what di/dt is? I see it occasionally in my textbook but I can't ever remember learning what it was. I looked through the indexes and couldn't find anything, so I guess maybe it is in one of the chapters my class skipped...
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