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Homework Help: Manufacturer of a 12V car headlight

  1. Sep 16, 2007 #1
    1. The problem statement, all variables and given/known data
    The manufacturer of a 12V car headlight specifies it will draw a current of 6A. You would like to check this claim with an ammeter designed to measure currents up to 10A and having a resistance of 0.1 Ohms.

    http://img168.imageshack.us/img168/7831/oaammeterqk3.th.png [Broken]
    What is the current readings in (A) of figure a) and b)

    2. Relevant equations


    3. The attempt at a solution
    So I think a has a value of 5.71 because 12/(2+.1)...is this wrong...and would figure b) be 0 since the fuse would blow? i'm basically lost.
    Last edited by a moderator: May 3, 2017
  2. jcsd
  3. Sep 16, 2007 #2


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    I think you are right on both. Why do you think you are lost?
  4. Sep 16, 2007 #3
    You did the first part right, which would give the current through the circuit for the ammeter and the headlight (if the manufacturer is right).

    In the second part the fuse will probably blow, the current would approximately be 120A, which gives a lot of power. Regardless of whether the fuse flows or not, you ought to figure out the current through there, don't just use my approximation. You can use Kirchoff's Voltage Law or Current Law, or both, with Ohm's law.
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