1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Series-Parallel-Series Circuits

  1. Oct 7, 2011 #1
    Hi Everyone. This is my first post on here. I'm currently doing an Electronic Engineering Diploma, but am struggling with just one thing (so far). Circuits and their equations. Everyone in that class are struggling, and I feel it may have something to do with the lecturers technique.

    Anyway, as part of our first assignment, we need to work out expected currents in ammeters, and potential differences across resistors. I can't attach a drawing for this, but will attempt to explain.

    I won't use the figures I have, as I'd like advice on the equations and mathematics that I need so that I can walk through it with my figures after.

    We have a DC battery (12V) going to R1 (100 Ohms). This then goes to three parallel resistors, R2-R4 (120 Ohms, 90 Ohms and 160 Ohms respectively). These then all lead to R5 (210 Ohms).

    The Ammeters are positioned at R1, R2, R3, and R4.

    There's another one that's a bit more complicated, but hopefully with some easy to understand advice on this one, I should be able to figure that one out.

    Anyway, any help would be greatly appreciated, and anyone who is able to explain this to me will forever go down as an absolute legend.

    Thanks in advance.
  2. jcsd
  3. Oct 7, 2011 #2


    User Avatar

    Staff: Mentor

    Welcome to the PF.

    For really simple questions, you can just use Ohm's Law, V=IR to figure out voltages and currents.

    And in some simpler resistor network questions, you can do series and parallel combination of resistors to simplify the network and help you solve it with just V=IR again.

    For more complicated circuits, you would usually use Kirchoff's Current Law (KCL) equations written for all of the nodes in the circuit, and then you just solve the simultaneous equations to get the currents and voltages in the circuit.

    So can you use this information to show us your circuit and show us how you are going to approach solving it?
  4. Oct 7, 2011 #3


    User Avatar

    Staff: Mentor

    Three resistors in parallel? I wonder how many ohms that would be equivalent to .....
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook