0
\$\begingroup\$

In the circuit attached in the image,I am unable to understand why R1,R2,R3,R4,R5 are not in parallel even though different current flows through them, any help would be appreciated enter image description here

\$\endgroup\$
6
  • 3
    \$\begingroup\$ ""even though different current flows through" if this is your definition what things in parallel are, then consider that the wire in one circuit also has a different current flowing through it than the wire in a completely different circuit. Obviously not in parallel. The definition is overly broad so as to be useless. Things are in parallel when the voltage across them is same. \$\endgroup\$ – DKNguyen Apr 15 at 4:48
  • \$\begingroup\$ How do I know if the voltage across them is the same? \$\endgroup\$ – KRATOS0990 Apr 15 at 4:50
  • 4
    \$\begingroup\$ Do they share the same node on both sides? If yes, parallel. If no, not parallel. \$\endgroup\$ – DKNguyen Apr 15 at 4:53
  • \$\begingroup\$ Thank you so much! I understood it very well why R1 and R3 are are not in parallel. \$\endgroup\$ – KRATOS0990 Apr 15 at 4:57
  • 1
    \$\begingroup\$ That's a different question so ask a new one. You'll need to specify at which nodes the resistance is being measured. \$\endgroup\$ – Transistor Apr 15 at 6:43
2
\$\begingroup\$

By definition, they are in parallel if and only if their respective terminals are tied together and nothing else is in the way. There is a more formal definition using topology but it's not very useful.

R1 is in parallel with R2: pin A of R1 is directly tied to pin A of R2, pin B of R1 is directly tied to pin B of R2;

R1 is not in parallel with R3: between pin A of R1 and pin A of R3 there is a battery and the K thingy (no idea of what that symbol mean).

Even if we reorder the circuit like this (Kirchoff says we can do it due to current law)

schematic

simulate this circuit – Schematic created using CircuitLab

R1 is still not in parallel with R3 since even if one terminal is in common between them, between the other there still is the source and ammeter

\$\endgroup\$
2
  • \$\begingroup\$ If I understood it correctly R1 is in parallel with R2 and R3,R4 and R5 are in parallel \$\endgroup\$ – KRATOS0990 Apr 15 at 7:16
  • 1
    \$\begingroup\$ Exactly, the parallel groups are then in series \$\endgroup\$ – Lorenzo Marcantonio Apr 16 at 8:15
2
\$\begingroup\$

There are two parallel circuits in series with each other. One parallel circuit is made up of R1 and R2, the other parallel circuit is R3,R4 and R5. So, the circuit equation for total resistance would be:

(1/(1/R1+1/R2)) + (1/(1/R3+1/R4+1/R5))

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.