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Voltage of bulb in the circuit

  1. May 26, 2015 #1
    1. The problem statement, all variables and given/known data
    What is the voltage of the bulb D? Given the total voltage supplied by the cells is 4 watts and each bulb is identical and has a resistance of 3 ohms

    2. Relevant equations
    V=IR

    3. The attempt at a solution
    By assuming bulb A,B, and C as a group , their effective resistance would be 2 ohms.
    Thus, the effective resistance of the circuit is Effective resistance of bulb A,B,C + resistance of Bulb D = 5 ohms
    Hence, the current across the circuit is total voltage supplied / effective resistance of the whole circuit = 4/5 A. Therefore, the voltage of bulb D is 4/5A x 3 ohms = 12/5 W

    *forgive me for my random attempt , since my teacher never taught me anything about this part
     

    Attached Files:

  2. jcsd
  3. May 26, 2015 #2

    SammyS

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    The units given in the statement of your problem don't make sense.

    What is the problem, word for word, as it was given to you?
     
  4. May 26, 2015 #3
    There is an error here. I think you mean the voltage supplied by the cells is 4 volts

    voltage is a measure of the EMF (electromotive force)
    w is for watts and it is a measure of energy over time (power) 1 watt = 1 joule for 1 second
     
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