Electronics > Beginners
Confused about voltage potentials & polarity in a circuit
Shock:
Firstly the bit about the mountains is confusing because there is no d. So of course between c to a takes you directly to the top of the mountain. Secondly in the schematic you must travel through d no matter if you go clockwise or anticlockwise. Thirdly the schematic states that c is 6V more positive than b and a is 4V more positive than b.
So in other words don't climb that mountain after looking at the schematic. :D
--- Quote from: Ronan on April 16, 2019, 11:08:18 pm ---What I don't get is if these are resistors, how is there a polarity since resistors aren't placed in a specific direction like LEDs are? Why would one be a + - and the next one be a - +?
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It is indicating by show voltage drops (the differences in voltage potential) that between the junctions the voltage goes more positive (higher) or more negative (lower).
--- Quote ---I'm confused about direction of current... electron flow... conventional flow...
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Typically you would choose conventional flow or whatever the text tells you. But in calculations it's not important as long as you stick to same direction calculating current in a circuit. But do use electron flow for the physics interpretation of what is occurring.
--- Quote ---What does it mean if power is consumed or generated in these two examples?
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The labelled junctions are showing the difference in relative voltage potentials between the resistors. Starting out for things to make a little more sense and fill in the gaps you need to learn Ohms law, Kirchhoff's current law and Kirchhoff's voltage law with the associated formulas.
I've attached a schematic as an example of how you could view the circuit. Note that even though its backwards it's essentially the same thing. The positive and negatives are in the actual direction of the voltage drops.
vk6zgo:
--- Quote from: IanB on April 17, 2019, 09:45:18 am ---
--- Quote from: Ronan on April 17, 2019, 12:25:00 am ---I get that each loop has to add to zero, but I'm still confused about the polarity of a resister which causes an addition or subtraction. How can there be a polarity for a resister, and how can that polarity change? As seen in this attachment.
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In your picture at the top of the thread the yellow things are NOT resistors. They are just unknown "things". Some of them could be (indeed must be) batteries or other voltage sources.
Resistors don't have polarity, but current has direction. In the direction that current is flowing through a resistor there must be a voltage drop in this direction.
As far as conventional current or electron flow is concerned, you should ignore electron flow and do not think about electrons or protons. You are not trying to be an atomic physicist, so these things are not relevant at the early stages of learning. They will just cause confusion. All electronics texts will use conventional current and conventional voltage so just follow standard conventions.
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For Pete's sake!
Sixteen year old kids in their first semester of study of Electrical Theory learnt how to apply the two different "current flow" concepts without getting confused, back in 1959, have we dumbed down that much?
Brumby:
--- Quote from: vk6zgo on April 18, 2019, 04:02:43 am ---For Pete's sake!
Sixteen year old kids in their first semester of study of Electrical Theory learnt how to apply the two different "current flow" concepts without getting confused, back in 1959, have we dumbed down that much?
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Is the OP undertaking a course of study that will have a planned teaching stream - or are they making their own way through the subject matter?
If they are following a course of study, then their teacher/lecturer can make the point clear - and they can then move on. In such a case, your point will have some validity.
HOWEVER, if they are muddling their way through on their own - then what we are trying to do is get them to follow the standard conventions that have been successfully used all around the world for decades so they can find their feet. Once they have a handle on that, they can progress.
Right now - it's enough that they know there is a difference - and that conventional current flow understanding will get them where they need to go.
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