# incorrect statment in the text

#### bfin

Joined May 29, 2006
3
Below is an exert from the text, and it is incorrect, see bold....

"Here, as in any one-source, one-load circuit, the voltage dropped across the load must equal the voltage supplied by the source, assuming zero voltage dropped along the resistance of any connecting wires. In other words, the load (inductor coil) must produce an opposing voltage equal in magnitude to the source, in order that it may balance against the source voltage and produce an algebraic loop voltage sum of zero. From where does this opposing voltage arise? If the load were a resistor, the opposing voltage would originate from the "friction" of electrons flowing through the resistance of the resistor. With a perfect inductor (no resistance in the coil wire), the opposing voltage comes from another mechanism: the reaction to a changing magnetic flux in the iron core.

Is this the correct way to state this? it does not coincide with resolving voltages into electric fields with certain amount of potential energy to move/interact with charge.
thoughts?

#### bfin

Joined May 29, 2006
3
should it not state, the voltage drop across the resistor is the drop in potential energy of the electric field (ability to move/interact with charges). the electric field is developed by the voltage source. the voltage across a resistance is not a voltage developed by moving electrons. it is the loss of energy equivalent to the source voltage, the loss due to friction.

#### thingmaker3

Joined May 16, 2005
5,083
Perhaps a better correction would be to simply replace the phrase "opposing voltage" with "opposing force."

#### Dave

Joined Nov 17, 2003
6,969
Thanks for the feedback.

I will alert DCrunkilton (the project co-ordinator) to your suggestion to get his comments.

Dave

#### bfin

Joined May 29, 2006
3
sounds good. let me know what you come up with.
the only reason i bring this up is voltage termed this way confuses students...and it can already be confusing enough.

#### Dcrunkilton

Joined Jul 31, 2004
422
I am proposing that the text in question be changed as follows:

Here, as in any one-source, one-load circuit, the voltage dropped across the load must equal the voltage supplied by the source, assuming zero voltage dropped along the resistance of any connecting wires. In other words, the load (inductor coil) must produce an opposing voltage equal in magnitude to the source, in order that it may balance against the source voltage and produce an algebraic loop voltage sum of zero. From where does this opposing voltage arise? If the load were a resistor (Figure attached (b)), the voltage drop originates from electrical energy loss, the “friction” of electrons flowing through the resistance. With a perfect inductor (no resistance in the coil wire), the opposing voltage comes from another mechanism: the reaction to a changing magnetic flux in the iron core. When AC current changes, flux Φ changes. Changing flux induces a counter EMF.

The original text may be seen in the beginning of this thread by bfin, or the full context in which the original text appears on allaboutcircuits may be seen at http://www.allaboutcircuits.com/vol_2/chpt_9/1.html
for reference.

I hope that this clears up objections to the original text. If not, please let me know so that we may clear up any points of confusion.