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Are \$R_1\$, \$R_3\$, and \$R_2\$ in series? or are \$R_1\$ and \$R_2\$ in parallel? I'm new to all this. Here's the circuit:

enter image description here

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4 Answers 4

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Well, \$\text{R}_3\$, \$\text{R}_4\$, \$\text{R}_5\$ and \$\text{R}_6\$ are in parallel and they are in series with \$\text{R}_1\$ and \$\text{R}_2\$.

schematic

simulate this circuit – Schematic created using CircuitLab

So the total resistance is:

$$\text{R}_\text{total}=\text{R}_1+\text{R}_2+\frac{1}{\frac{1}{\text{R}_3}+\frac{1}{\text{R}_4}+\frac{1}{\text{R}_5}+\frac{1}{\text{R}_6}}$$

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  • \$\begingroup\$ so i get the equivalent resistance of R3 R4 R5 and R6, then i add it to r1 and r2, so r1 and r2 are in series ? \$\endgroup\$
    – AhmadBenos
    Mar 26, 2020 at 14:50
  • \$\begingroup\$ @AhmadBenos See my edit \$\endgroup\$ Mar 26, 2020 at 14:51
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    \$\begingroup\$ Got it! Thanks a lot. \$\endgroup\$
    – AhmadBenos
    Mar 26, 2020 at 14:51
  • \$\begingroup\$ @AhmadBenos You're welcome, I'm glad that I could be of any help. \$\endgroup\$ Mar 26, 2020 at 14:54
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Just for a definitional answer:

  • Two resistors are in parallel if each terminal of resistor A is connected to the terminals of resistor B
  • Two resistors are in series if only one terminal of resistor A is connected to a terminal of resistor B (and their common point isn't connected to anything else).

Just because it's worth saying: it doesn't matter how you draw them, it only matters how you connect them.

As for solving these kinds of problems, you can always replace two parallel resistors with another resistor of value 1/( 1/Ra + 1/Rb ), regardless of what other connection there might be. (Series resistors, on the other hand, can only be replaced by a single resistor if nothing else is connected to their common point.)

schematic

simulate this circuit – Schematic created using CircuitLab

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  • \$\begingroup\$ I want to deny the fact that the 3rd figure of parallel figures is not series but parallel.. \$\endgroup\$
    – muyustan
    Jun 6, 2020 at 14:05
  • \$\begingroup\$ The definition of series is not correct. Elements are in series if just one terminal of each element is connected to together and nothing else is connected at that point. I know that you say that this is a condition for resistors to be combined, but it is actually a condition for them to be in series. \$\endgroup\$ Jun 6, 2020 at 17:21
  • \$\begingroup\$ @ElliotAlderson thanks for your comment. How would you describe the two resistors of a potential divider across say power and ground? We add their resistances to calculate the load they present to the power supply, because they are in series. Even when we connect (say) the base of some transistor there, those resistors are still in parallel. How would you describe them? \$\endgroup\$
    – jonathanjo
    Jun 7, 2020 at 11:24
  • \$\begingroup\$ @muyustan thanks for your comment, but I'm not sure what you're saying. Are you saying R3a and R3b are not in parallel? \$\endgroup\$
    – jonathanjo
    Jun 7, 2020 at 11:25
  • \$\begingroup\$ Oh no, your figure is correct. They are in parallel. It is just that, they look like they are in series intuitively \$\endgroup\$
    – muyustan
    Jun 7, 2020 at 11:47
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Resistors R3, R4, R5 and R6 are connected in parallel. And this circuit is connected in series to R1 and R2.

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  • \$\begingroup\$ Oh okay! Thanks \$\endgroup\$
    – AhmadBenos
    Mar 26, 2020 at 14:51
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Actually R3,R4,R5,R6 are in parallel combination as the voltage across the resistors is same and the combination and R1,R2 are in series as the current will be same through them

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  • \$\begingroup\$ Isn't this exactly what all of the answers said? \$\endgroup\$ Mar 28, 2020 at 15:17

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