# Effect of resistance on voltage flow in a wire

• nallur
In summary, the conversation discusses the concept of voltage flow and how it relates to Ohm's law. The individual is confused about how increasing resistance can lead to an increase in voltage, and is seeking an explanation for how this process works at the atomic level. They also question the direction of current flow in a scenario with unequal resistance.
nallur
Hey guys!

Any answers will be much appreciated!

The following is a deep conceptual issue I have. The diagram is a bit crude but will suffice I think.
Note: Had drawn the circular 'electric field' at the time, to just help myself over my confusion. Feel free to ignore it.

As per Ohm's law V = IR. In the above scenario there is greater resistance at point 1 then there is at point 2 (as shown on the diagram). The charges (q1 and q2) and so the current flowing through both points are the same.
Voltage is defined as the strength of an electric field to cause current flow. And current flow is nothing but the movement of charges i.e. Movement of electrons.
So following on, this means that according to Ohm's law of V = IR, there is a greater voltage at point 1 then there is at point 2. Therefore voltage will 'flow' from point 1 to point 2 i.e., From high to low.

This is where my issue arises. With there being greater resistance for the electrons to flow from point 1 how is it that the electrons will go from point 1 to point 2? Shouldn't it be the other way around. I don't conceptually understand how the greater resistance in this way causes voltage flow and so current flow from point 1 to 2. From my definition of voltage given, the greater resistance at point 1 would actually make it harder for the current to flow from point 1 to 2. Conversely the lower resistance at point 2 would make it easier for the current to flow from point 2 to 1.

Yet, and as per Ohm's law, voltage is greater at point 1 so current somehow flows down?

It is kind of a question within another question, so had to explain myself a bit. I am really not knowledgeable in electrical phenomena, so this may very well be a basic matter that I don't know!

This is not clear at all. Could you simply describe the setup you are considering?

"I don't conceptually understand how the greater resistance in this way causes voltage flow..."

What is Voltage flow?

DrClaude said:
This is not clear at all. Could you simply describe the setup you are considering?

Sorry for it not being clear to you. Basically in a nutshell, my confusion is all about how Ohm's law works in reality, i.e., how does increasing resistance increase the voltage at the level of current and electron flow? The equation is V= IR but I don't see how increasing the resistance actually increases voltage!

In the above diagram I haven't shown a battery or a power source but say current was flowing through the wire and one end of the wire has more resistance then the other end, which way would the current flow within the wire? (The current being the same throughout the wire) From Ohm's law we know that V = IR so the end of the wire where there is more resistance would have a greater voltage potential, correct?

Following on simply, voltage flow occurs from a point of high voltage to a lower voltage. If I am right up until now then what I am conceptually confused is how, despite Ohm's Law of V = IR, can increasing the resistance increase voltage potential. Because, resistance would repel or obstruct the flow of electrons. Yet this somehow increases voltage potential?
Voltage is the measure of how much electrons can move (current) so I don't see at the atomic scale, how increases resistance can help in moving electrons and increase voltage potential?

Have tried my best to make it clear, please get back to me.

nallur said:
Hey guys!

Any answers will be much appreciated!

The following is a deep conceptual issue I have. The diagram is a bit crude but will suffice I think.
Note: Had drawn the circular 'electric field' at the time, to just help myself over my confusion. Feel free to ignore it.

View attachment 112786
As per Ohm's law V = IR. In the above scenario there is greater resistance at point 1 then there is at point 2 (as shown on the diagram). The charges (q1 and q2) and so the current flowing through both points are the same.
Voltage is defined as the strength of an electric field to cause current flow. And current flow is nothing but the movement of charges i.e. Movement of electrons.
So following on, this means that according to Ohm's law of V = IR, there is a greater voltage at point 1 then there is at point 2. Therefore voltage will 'flow' from point 1 to point 2 i.e., From high to low.

This is where my issue arises. With there being greater resistance for the electrons to flow from point 1 how is it that the electrons will go from point 1 to point 2? Shouldn't it be the other way around. I don't conceptually understand how the greater resistance in this way causes voltage flow and so current flow from point 1 to 2. From my definition of voltage given, the greater resistance at point 1 would actually make it harder for the current to flow from point 1 to 2. Conversely the lower resistance at point 2 would make it easier for the current to flow from point 2 to 1.

Yet, and as per Ohm's law, voltage is greater at point 1 so current somehow flows down?

It is kind of a question within another question, so had to explain myself a bit. I am really not knowledgeable in electrical phenomena, so this may very well be a basic matter that I don't know!
nallur said:
Sorry for it not being clear to you. Basically in a nutshell, my confusion is all about how Ohm's law works in reality, i.e., how does increasing resistance increase the voltage at the level of current and electron flow? The equation is V= IR but I don't see how increasing the resistance actually increases voltage!

In the above diagram I haven't shown a battery or a power source but say current was flowing through the wire and one end of the wire has more resistance then the other end, which way would the current flow within the wire? (The current being the same throughout the wire) From Ohm's law we know that V = IR so the end of the wire where there is more resistance would have a greater voltage potential, correct?

Following on simply, voltage flow occurs from a point of high voltage to a lower voltage. If I am right up until now then what I am conceptually confused is how, despite Ohm's Law of V = IR, can increasing the resistance increase voltage potential. Because, resistance would repel or obstruct the flow of electrons. Yet this somehow increases voltage potential?
Voltage is the measure of how much electrons can move (current) so I don't see at the atomic scale, how increases resistance can help in moving electrons and increase voltage potential?

Have tried my best to make it clear, please get back to me.
You have some very big misconceptions about how electricity works. We will do our best to help you get things straight.

What resources have you been using to learn about how basic electricity and Ohm's Law work? Can you give us a couple of links to what you have been reading?

https://en.wikipedia.org/wiki/Ohm's_law
http://hyperphysics.phy-astr.gsu.edu/hbase/electric/resis.html

Resistance does not exist at a point. It exists between two separated contact points on a material. The resistance between those points determines how much current flows when you apply a voltage between those two points.

nallur and davenn

Actually, my misconceptions are rather due to ignorance of the matter, its not that I read anything particular on electricity. However now having gained interest I would like like to start. I am thinking of reading a physics book to begin. Perhaps other things like YouTube videos and other websites like the one you shared could do me well.

You mentioned, "Resistance does not exist at a point. It exists between two separated contact points on a material. The resistance between those points determines how much current flows when you apply a voltage between those two points" - Thanks for this clarification, I now see that if there is more resistance between two points then there will be a greater voltage potential.

However - I don't understand why resistance doesn't exist at a point. For their to be resistance in between two points there must be resistance at each and every other point (in space) along the way also shouldn't there? Applying this to my situation above I simply see (and now remember from what was taught in high school) that electrons or current follows the path of least resistance. So as there is greater resistance in point 2 compared to point 1 current will flow down. This is fairly logical is it not?

Thanks for your links provided, I will check them out and get back to you if there is anything!

nallur said:
Thanks for this clarification, I now see that if there is more resistance between two points then there will be a greater voltage potential.
That's not really the best way to think about it. Usually in these Ohm's Law situations, the resistance is constant and set by the geometry and resistivity of the object, and the current is dependent on the voltage applied, V=I*R. You can apply a known current and measure the voltage that results, but that is a less common way to measure the resistance.
nallur said:
However - I don't understand why resistance doesn't exist at a point. For their to be resistance in between two points there must be resistance at each and every other point (in space) along the way also shouldn't there?
It's better to think of resistance existing across a volume or volume element. In fact, we calculate the resistance of unusual shapes by dividing the shape up into little cubes or thin slices through the shape, and add up the resistance pieces along the path between the two electrical contact points.

nallur
berkeman said:
That's not really the best way to think about it. Usually in these Ohm's Law situations, the resistance is constant and set by the geometry and resistivity of the object, and the current is dependent on the voltage applied, V=I*R. You can apply a known current and measure the voltage that results, but that is a less common way to measure the resistance.

Yes, so you're saying that in a circuit for example, the resistance along the wire is the same. The 'points' of resistance in a circuit would then be where the resistors are!

berkeman said:
It's better to think of resistance existing across a volume or volume element. In fact, we calculate the resistance of unusual shapes by dividing the shape up into little cubes or thin slices through the shape, and add up the resistance pieces along the path between the two electrical contact points.

Right, so this must be just some multi-integral calculus you are referring to aren't you? Also, where can one learn or come across the foundational derivations for quantities like resistance and voltage etc. Is it through study of Maxwell's equations? This is where even the very common Ohm's Law is derived isn't it!

Lastly, have just purchased the book "Introductory circuit analysis 10th Ed" by Robert Boylestad. From the reviews given it seems to be a SUPERB book on both electronics and circuit analysis for total beginners. Am stoked about learning from it.

Thanks again!

berkeman
nallur said:
Right, so this must be just some multi-integral calculus you are referring to aren't you? Also, where can one learn or come across the foundational derivations for quantities like resistance and voltage etc. Is it through study of Maxwell's equations? This is where even the very common Ohm's Law is derived isn't it!
It can be an integral or a summation. Here is a good starting point:

http://web.mit.edu/viz/EM/visualizations/coursenotes/modules/guide06.pdf

Post if you have more questions. We are glad that you are learning so much and so well now.

Thank you much, you've been patient! Will do!

## 1. How does resistance affect voltage flow in a wire?

Resistance is a measure of how difficult it is for current to flow through a wire. As resistance increases, the voltage flow decreases. This is because the resistance creates a barrier that the electrons must overcome, reducing the amount of current that can flow through the wire.

## 2. What is the relationship between resistance and voltage flow?

The relationship between resistance and voltage flow is inverse. This means that as resistance increases, voltage flow decreases, and vice versa. This relationship is described by Ohm's Law: V = IR, where V is voltage, I is current, and R is resistance.

## 3. How does the length of a wire affect resistance and voltage flow?

The longer the wire, the higher the resistance and the lower the voltage flow. This is because a longer wire provides more obstacles for the electrons to overcome, resulting in a higher resistance. As a result, the voltage flow will decrease due to the increased resistance.

## 4. Does the material of the wire affect resistance and voltage flow?

Yes, the material of the wire can affect resistance and voltage flow. Materials with higher resistance, such as copper, will have a lower voltage flow compared to materials with lower resistance, such as silver.

## 5. How does temperature affect resistance and voltage flow in a wire?

As temperature increases, so does resistance. This is because the increased temperature causes the atoms in the wire to vibrate more, creating more obstacles for the electrons to pass through. As a result, the voltage flow will decrease due to the increased resistance.

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