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Homework Help: Learner what is resistance value here.

  1. Jun 20, 2012 #1
    hello people,

    in this circuit the voltage be 50 millivolts and R2 is 5 gigaohms how much should be R1 and R3 so that my output current is 10 picoAmps.
    R2 is load here.


    Attached Files:

  2. jcsd
  3. Jun 20, 2012 #2


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    Gold Member

    Start with voltage division....and V=IR.

    Show a little work or thought before we help....
  4. Jun 20, 2012 #3
    getting a small doubt with the resistors,
    which are parallel and in series?
    can you tell me the total voltage please?
  5. Jun 20, 2012 #4


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    Gold Member

    You are not listening. As psparky said, you need to show some work on your own before you get help here.

    It is against the forum rules to just spoon-feed people answers to homework problems. Please read the forum rules.
  6. Jun 20, 2012 #5
    just tell me which are in parallel and which are in series thats it.
    i will do the rest of it.
  7. Jun 20, 2012 #6
    You need to follow the nodes. Always best to redraw the circuit in a manner that is "more obvious" to you. And like I said, this is best done by following the nodes. KVL should give you the answer. However, make sure you've drawn the circuit correctly.
  8. Jun 20, 2012 #7


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    Gold Member

    I'll give ya some hints.......

    Step 1.

    What voltage do you need at the blue node to find your desired current. Use V=IR.

    Step 2.
    Pick a value for R3. Now use voltage division to find your last resistor value...using the voltage you just found at the blue node.

    BTW...what is your return path for your load? How does it get back to the battery?
    I'm guessing the bottom of R2 hooks to the top of R1......making R1 and R2 in parllel?

    And if that's the case.....I think you will need to combine R1 and R2 in parallel before using voltage division.
    Last edited: Jun 20, 2012
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