Positioning of Resistors in Series

[Richie Smash]

Hi, I'm aware that the total resistance in a series connection is the sum of all the resistors involved, and that the current is the same throughout, and that the voltage will be different for each resistor but the total voltage will be their sum as well.

However, I would like to inquire, does changing the POSITION of the resistors, somehow change the total resistance?

(Still in introductory physics)

 

[anorlunda]

does changing the POSITION of the resistors, somehow change the total resistance?

No.

 

[berkeman]

Hi, I'm aware that the total resistance in a series connection is the sum of all the resistors involved, and that the current is the same throughout, and that the voltage will be different for each resistor but the total voltage will be their sum as well.

However, I would like to inquire, does changing the POSITION of the resistors, somehow change the total resistance?

(Still in introductory physics)

As anorlunda says, with resistors the answer would generally be no. One exception might be if they were oriented vertically so that the heat from the bottom resistor heated up the top resistor via convection more or less depending on the power dissipation of each resistor. But that would be an extreme corner case, with an extremely small effect, I think.

It's good that you ask such questions while you are learning. The answer for inductors in general is quite different. Can you say why the positions and orientations of two inductors in series (or even in parallel) can affect the inductance of each and the total inductance?

 

[Richie Smash]

As anorlunda says, with resistors the answer would generally be no. One exception might be if they were oriented vertically so that the heat from the bottom resistor heated up the top resistor via convection more or less depending on the power dissipation of each resistor. But that would be an extreme corner case, with an extremely small effect, I think.

It's good that you ask such questions while you are learning. The answer for inductors in general is quite different. Can you say why the positions and orientations of two inductors in series (or even in parallel) can affect the inductance of each and the total inductance?

Well I only just briefly read about inductors, but I would say the positions matter because they store energy in the form of a magnetic field, and according to Fleming's left and right hand rules, the force, current and magnetic fields are at right angles to each other, so I would think this is why orientation is important.

 

[berkeman]

Well I only just briefly read about inductors, but I would say the positions matter because they store energy in the form of a magnetic field, and according to Fleming's left and right hand rules, the force, current and magnetic fields are at right angles to each other, so I would think this is why orientation is important.

Good. Depending on the construction technique used in the inductor, there can be some of the internal magnetic field that leaks out and can couple to nearby inductors. So when using multiple inductors in a circuit, the spacing and orientations can be very important (to get the inductances you want). You can use shielded inductors, but they are more expensive than their unshielded versions.

When you have to place 2 inductors close to each other, often it's a good idea to orient them at right angles to each other. Can you say why this may help to mitigate the parasitic B-field coupling between them?

https://thumb9.shutterstock.com/dis...conductor-made-of-a-copper-wire-474690208.jpg

 

[Richie Smash]

Good. Depending on the construction technique used in the inductor, there can be some of the internal magnetic field that leaks out and can couple to nearby inductors. So when using multiple inductors in a circuit, the spacing and orientations can be very important (to get the inductances you want). You can use shielded inductors, but they are more expensive than their unshielded versions.

When you have to place 2 inductors close to each other, often it's a good idea to orient them at right angles to each other. Can you say why this may help to mitigate the parasitic B-field coupling between them?

https://thumb9.shutterstock.com/dis...conductor-made-of-a-copper-wire-474690208.jpg
View attachment 218106

Well... I can visualize it, and the two inductors would then be perpendicular to each other, so I would assume the fields have less interference, and perhaps it's something to do with the interaction of the poles when they are at right angles, I'm just trying to think here without looking it up, I know when two fields interact, the top field is stronger than the one below it... so perhaps when they are at right angles, the field of the horizontal facing inductor will have a lesser effect, as the two fields are moving in the same direction above perhaps...

 

[berkeman]

Well... I can visualize it, and the two inductors would then be perpendicular to each other, so I would assume the fields have less interference, and perhaps it's something to do with the interaction of the poles when they are at right angles, I'm just trying to think here without looking it up, I know when two fields interact, the top field is stronger than the one below it... so perhaps when they are at right angles, the field of the horizontal facing inductor will have a lesser effect, as the two fields are moving in the same direction above perhaps...

It's mainly that the B-field from each inductor pierces the other inductor at mostly a right angle, and what doesn't go through at a right angle cancels out, so there is no net coupling from one coil to the other. If they are in the shape of a "T", then half of the B-field from the bottom inductor goes one way through the top coil, and the other half of the B-field goes the other way through the top coil.

 

[CWatters]

However, I would like to inquire, does changing the POSITION of the resistors, somehow change the total resistance?

Addition is "commutative" so the order doesn't matter. For example 1+2+3+4 = 3+4+1+2 = 10

https://en.wikipedia.org/wiki/Commutative_property