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Homework Help: Find the resistance of the lamp

  1. Oct 27, 2008 #1
    1. The problem statement, all variables and given/known data
    Two 1.50 V batteries-with their positive terminals in the same direction-are inserted in series into the barrel of a flashlight. One battery has an internal resistance of 0.255 ohms, the other has a resistance of 0.153 ohms. When the switch is closed, a current of 600 mA occurs in the lamp. (a) What's the lamps resistance? (b) What fraction of the chemical energy transformed appears as internal energy in the batteries?

    2. Relevant equations

    3. The attempt at a solution
    I'm not sure how to start the problem. Please Help.
  2. jcsd
  3. Oct 27, 2008 #2
    a) By Ohm's Law, V = IR. So you know I, you know V, R is the sum of the two internal resistances and the flashlight so it can be easily solved.

    b) Not sure what this is asking exactly.
  4. Oct 27, 2008 #3


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    Staff Emeritus
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    Gold Member

    For the last part compute the energy consumed by the interal resistance.
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