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Math Help - How to solve this simple circuit ?

  1. #1
    Junior Member silvercats's Avatar
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    How to solve this simple circuit ?

    http://oi51.tinypic.com/2nk2qtg.jpg

    I was able to find I1:
    simplified and got total resistance=10/3 and V=10(coz parallel)
    by putting V=IR
    I got 10=I(10/3)
    I=3A

    How to find the I2?I think my I1 is wrong too.
    thanks for reasing.
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  2. #2
    Senior Member BAdhi's Avatar
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    Have you learned a theory called Kirchhoff's(not sure about the spellings) two laws?
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  3. #3
    Junior Member silvercats's Avatar
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    Quote Originally Posted by BAdhi View Post
    Have you learned a theory called Kirchhoff's(not sure about the spellings) two laws?
    have heard that name before.IDK,I have learned some laws and hard to remember what is what :/
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  4. #4
    Senior Member BAdhi's Avatar
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    Here you have to use the Kirchoff's first law (or the current law), which is on any joint of the circuit, \sigma I=0.

    From this you'll get the current flowing through the middle resistor as I_1-I_2

    now use the Kirchoff's Voltage law which is on any closed circuit, \sigma E=0

    add this equation to two closed circuits to find I_1 and I_2
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  5. #5
    Junior Member silvercats's Avatar
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    I know that ΣE=ΣIR(that is the kirchhoff's law I guess?) thing.Did according to that and never got the answer in the book .I don't understand above thing too ups
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  6. #6
    Senior Member BAdhi's Avatar
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    Quote Originally Posted by silvercats View Post
    I know that ΣE=ΣIR(that is the kirchhoff's law I guess?) thing.
    if this is what you've used in your first post, it is not Kirchoff's law, it is Ohm's law. Kirchoff's law is a developed from the Ohm's law.

    Can you describe in detail how you got I1
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  7. #7
    Junior Member silvercats's Avatar
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    parallel 4Ω and 2Ω: (1/4)+(1/2)=1/R =4/3Ω
    that 4/3Ω and left side's 2Ω are =4/3 + 2 =10/3Ω
    because there are two parallel batteries ,10v and 10v =10 ( <<< this is wrong i think)

    and

    by putting V=IR
    I got 10=I(10/3)
    I=3A
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  8. #8
    Senior Member BAdhi's Avatar
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    you cannot simplify resistors that easily, refer Kirchhoff's circuit laws and your text books, I guess you've already been taught about this laws
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