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Thread: [HELP WANTED] Physics: Electricity

  1. #1
    Charlotte's Avatar
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    Exclamation [HELP WANTED] Physics: Electricity

    A 120-V circuit contains a 20.0-Ω resistor and a 40.0-Ω resistor connected in parallel.
    a) What is the current through the 40.0-Ω resistor?
    b) What is the total current in the circuit?


    Any help at all is appreciated!

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    bamag's Avatar
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    Just wondering, what level of physics is this?
    I think you can use Ohm's Law.
    I=V((1/R1)+(1/R2)) where I is current, V is voltage, and R is resistance.
    I haven't done much on electricity so I'm not too sure.

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    Based on what you provided, you can conclude that the total current is 9 Ohms.

    120(1/20+1/40)
    120(3/40)
    9

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    Ohm is the SI unit for Resistance and not Current which is A for amperes

    The formula in Ohm's law I = V/R is applied to each resistor in a parallel circuit to get the current following at that section.
    The total current in a parallel circuit is the total current from each section of the parallel circuit.

    Therefore,
    a)What is the current through the 40.0-Ω resistor?
    120V/40Ω= 3A

    b)What is the total current in the circuit?
    Current at 20Ω resistor - 120V/20Ω= 6A
    Total current in the circuit - 6A+3A= 9A

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