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Ohms Law

  1. Feb 7, 2008 #1
    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. Which of the two figures below represents a circuit where the ammeter correctly measures the current in the headlight?
    OA-Ammeter.bmp

    a. Circuit a.
    b. Circuit b.

    How much current (in A) would flow in the ammeter for Circuit a?

    i thought A would equal V/R, which in this case i thought would be 12/.1= 120 amps... but this is not correct. please help!

    How much current (in A) flows through the ammeter for Circuit b?
     

    Attached Files:

    Last edited: Feb 7, 2008
  2. jcsd
  3. Feb 8, 2008 #2
    The pictures haven't authenticated yet, but ammeters are used in series with the load (headlight) so that the combined resistance of the circuit is 0.1ohm + the resistance of the headlight which is supposedly 12V/6A = 2ohm. If the headlight truly is 2ohm, you should see slightly less current than 6A with the ammeter hooked up (it's your job to find how much though).
     
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