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Homework Help: Calculating Resistance of a Light Bulb

  1. Jul 10, 2011 #1
    1. The problem statement, all variables and given/known data
    Hook up a round bulb to two D batteries. Measure the voltage drop across the bulb. Measure the current flowing through the bulb. Calculate the resistance of the bulb. V=2.25v; I=0.24A

    2. Relevant equations

    3. The attempt at a solution
    Is the "V" in the equation the number the multimeter gave me (2.25v) or do I use 3.0v-2.25v=0.75? In the first case R=9.3. Using 0.75v R=3.13.
  2. jcsd
  3. Jul 10, 2011 #2


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    Welcome to PF!

    Hi Kryttle! Welcome to PF! :wink:
    Yes. :smile:

    In V = IR (Ohm's Law), the https://www.physicsforums.com/library.php?do=view_item&itemid=301" drop and the resistance are both measured across the (same) component. :wink:
    Last edited by a moderator: Apr 26, 2017
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