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Difference between lights connected in series and parallel

  1. Jan 21, 2016 #1
    1. The problem statement, all variables and given/known data

    When two same lamps are connected with the same battery. Their lighting will be greater when they are connected in series or parallel?
    2. Relevant equations
    Series U=U1+U2+U3+...
    I=I1=I2=I3...
    Parallel U=U1=U2=U3...
    I=I1+I2+I3+...

    3. The attempt at a solution
    The answer is when they are connected in parallel. But why?
    Is it related to the tension or intensity or power?
     
  2. jcsd
  3. Jan 21, 2016 #2

    gneill

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    Staff: Mentor

    In a very simple view, the brightness of a light bulb is proportional to the power it consumes. The power is determined by the voltage across the bulb and the current through it: ##P = V I##.

    If you assume that the bulb has a constant resistance (again, a simple view), then Ohm's Law tells you that the current through it is related to the voltage across it by ##I = V/R##.

    Use your knowledge of how voltage and current are distributed among components in series and parallel circuits.
     
  4. Jan 21, 2016 #3
    So we can write P=U^2/R
    U is the same in each resistance in parallel, but it divides in resistances in series. So it is greater in resistances in parallel. This way P is greater when they are connected in parallel. Am I right?
     
  5. Jan 21, 2016 #4

    gneill

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    Staff: Mentor

    Yes, that's a correct analysis.
     
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