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Homework Help: Series and parallel circuits

  1. Mar 12, 2009 #1
    2.Two resistors of 5 ohms and 20 ohms are connected in parallel across an ideal source of 20 V. The current supplied by the source is

    a) .4 A, B) 5 A c) 20 A d) 1 A e) none of these

    My work
    R1 = 5 ohms
    R2 = 20 ohms
    V = 20 v
    I = ?

    V = IR
    V/R = I = 20 V / 114 ohms = 80 amps

    3. The problem statement, all variables and given/known data[/b]
    Two 2 ohm resistors are in parallel. What is their equivilant resistance?

    1/2 ohms + 1/2 ohms = 1 ohm. Is this correct?

    4)A 20 volt potential is applied across a series combination of a 10 ohm and a 30 ohm resistor. The current in the 10 ohm resistor is a) .5 amps, b) .67 amps c) 1.0 amps d) 2.0 amps

    P = I^2R
    I = THE SQUARE ROOT OF (10 ohms/20 V)

    5) a 120 volt home electrical socket has 3 wires. How many of these wires would give yo ua shock if you were grounded when yo utouched them one wire at a time?

    a) one b) two c) three

    I think it is one.
  2. jcsd
  3. Mar 12, 2009 #2


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    Homework Helper

    For 2 you need to use the relationship that

    1/Req = 1/r1 + 1/r2

    No idea where your 114 came from.
  4. Mar 12, 2009 #3
    Woudl anyone mind showing me and hleping me solve these problems?
  5. Mar 12, 2009 #4


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    Homework Helper

    I've already helped you with 2).

    Doing the problems for you isn't exactly going to help you learn the material.
  6. Mar 12, 2009 #5
    THanks anyways i got help on Yahoo Answers
  7. Mar 12, 2009 #6


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    Homework Helper

    As long as you get to uplink to Yahoo Answers for your exams you'll be all set then.

    Good luck.
  8. Mar 13, 2009 #7


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    Science Advisor
    Homework Helper

    Just to be completely scientifically accurate: you mean you got answers at Yahoo Answers. Which is good, I suppose, since that's what the name claims they'll give you.

    As LowlyPion said, good luck on your exam.
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