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Re: [Phys-L] voltage rise/drop terminology

On Wednesday, April 09, 2014 12:59 PM, jbellina wrote:
<<<
Sorry, but I think the source/sink language just supports the very conception you are trying to eliminate. There is some very nice material in the beginning of McDermott's Physics by Inquiry that helps students develop a good understanding of current flow in simple circuits. You might want to look at that.


If you are saying that we should restrict our language to only "voltage across", I can see the value in that.

On Wednesday, April 09, 2014 3:23 PM, Bernard Cleyet wrote:
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bc dosen't understand why sources and sinks are wrong****
**** A sink doesn't mean the E is "lost"; just transformed or goes somewhere else, likewise the source is another transformation, e.g. "chem." E to elec. E or KE to elec. E. No???


To which Philip Keller responded:
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When I see "source" I think of a spigot with something flowing out. When I see "sink" I think of a drain with something disappearing. When teaching Gauss's law, I've said that if the net flux through a closed surface isn't zero, there must be a "source" or a "sink" for field lines. In this sense, the field lines really do appear out of one and disappear into the other. I don't think I would choose that imagery for batteries and resistors.


Would there be any problem with defining the voltage as the power per current?

If so, why?

If not, could we say power drop/rise per current? Power source/sink per current? Power across the resistor per current? Which do you prefer?

Robert A. Cohen, Department of Physics, East Stroudsburg University
570.422.3428 rcohen@esu.edu http://www.esu.edu/~bbq



On Apr 9, 2014, at 12:39 PM, Robert Cohen wrote:

Though it seems straightforward to migrate from their incorrect view to the exactly correct view, I have found little success in my polishing attempts so far.

It is for this reason that I am considering the change in terminology. If no one can see anything wrong with "sources" and "sinks", then I will try that, as it seems more consistent with the view that energy enters the circuit via the battery and exits the circuit via the resistors without necessarily needing to specify that it travels in any particular direction ALONG the circuit.

Robert A. Cohen, Department of Physics, East Stroudsburg University
570.422.3428 rcohen@esu.edu http://www.esu.edu/~bbq