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!

Circuit with two batteries

  1. May 16, 2015 #1
    1. The problem statement, all variables and given/known data
    http://imgur.com/6Cds4YF [Broken]

    What will the ammeter read when the switch is closed?

    2. Relevant equations
    V = IR

    3. The attempt at a solution
    I already calculated the emf of the battery one the left to be about 27 V.
    It seems that the answer to the question is as simple as using V = IR where V is from the battery.
    So I = V/R = 25/50 = 0.5 A.

    I don't understand why the other battery to the left and the other resistors don't affect the current through the ammeter though. Wouldn't using the numbers for calculating the current, assume that the only item in the circuit is a 25 V battery and one 50 ohm resistor?
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. May 16, 2015 #2


    User Avatar
    Gold Member

    What is the voltage across the 50 ohm resistor? What factors affect what that voltage is?
  4. May 17, 2015 #3

    rude man

    User Avatar
    Homework Helper
    Gold Member

    Use principle of superposition, one battery at a time.
  5. May 17, 2015 #4


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    If the battery has no internal resistance it behaves like an ideal voltage source. Think about the properties of an ideal voltage source.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted