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: Need help on series circuts

  1. May 10, 2010 #1
    _________300ma__
    |........................ |
    |........................ ∏ L1
    _ +......................| R1
    9v.......................|.............................. ignore the dots in the middle
    - -...................... ∏ L2
    |..........................| 2R
    |________________|

    Find the:

    The value of R

    The total resistance

    and any other answers this question might yield

    Thanks a lot.

    only question i got wrong in a test. :(
     
    Last edited: May 10, 2010
  2. jcsd
  3. May 10, 2010 #2
    300ma = 9/R
    Total Resistance = 30Ohms

    30/2 = 15ohms each resistor?
     
  4. May 10, 2010 #3

    Redbelly98

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    I am redrawing the circuit, hopefully this is easier to look at:
    Code (Text):
     ________300ma__
    |               |
    |               ∏ L1  
    _ +             |  R1      
    9v              |
    - -             ∏ L2
    |               |  2R
    |_______________|
    Are you sure you reproduced the question accurately? It's weird to have those inductors in there, without for example a switch that closes at time t=0 or something along those lines. Also, is the 300 mA the current at some specific time, or after a long time has passed?

    Also, did you mean to say 2R or R2 in the figure?

    If R were 300 ohms, then the current would be 9/300≠0.3A.
     
    Last edited: May 10, 2010
  5. May 17, 2010 #4

    I mean 30 Ohms, the O makes it look like a 300
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook