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Current flowing through LED

  1. Feb 4, 2016 #1
    1. The problem statement, all variables and given/known data
    Screen Shot 2016-02-04 at 11.54.34 AM.png

    2. Relevant equations
    V=IR

    3. The attempt at a solution
    I'm not sure if this is right, but I did this problem by finding the current in the 300ohm resistor by doing I=5V/300ohms = .0166A and since they are in series they have the same current. I don't think that is right though. The LED is 2V, so I'm not sure how to treat that.
     
  2. jcsd
  3. Feb 4, 2016 #2
    The voltage across the resistor is not 5 v. What type of circuit is this (series / parallel). What do you know about the voltage and current in that type of circuit?
     
  4. Feb 4, 2016 #3
    It's a series circuit right? In series current is the same throughout the circuit and voltage is different. For parallel voltage is the same and current is different.
     
  5. Feb 4, 2016 #4

    cnh1995

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    Homework Helper

    Right. What is the voltage across resistor then?
     
  6. Feb 4, 2016 #5
    Im not sure. Would it be 3V? Va-Vb?
     
  7. Feb 4, 2016 #6
    Good, Now, What is the current through the resistor
     
  8. Feb 4, 2016 #7
    .01A. So does that mean that .01A are flowing through the LED?
     
  9. Feb 4, 2016 #8

    cnh1995

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    Homework Helper

    Yes.
     
  10. Feb 4, 2016 #9
    In a series circuit is current constant?
     
  11. Feb 4, 2016 #10
    Yes. same current, different voltage.
     
  12. Feb 4, 2016 #11
    There you go. Good job!!
     
  13. Feb 4, 2016 #12
    Thanks!!!
     
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