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Homework Help: Circuit with diode

  1. Apr 14, 2013 #1
    I attached the circuit.
    I need to find I_1, Voltage drop across R1, voltage drop across R2, and I_2. We're assuming the diode is 'not' ideal.

    Vin=5V. R1=R2=1kohm

    voltage across R2=Vin=5V

    The real diode drops about 0.7 V. So using voltage divider gives voltage across R1=(R1/(R1+R3))*(5-0.7)=1.43V

    Then I1=1.43/1k=1.43mA

    Is this the right idea?

    Attached Files:

  2. jcsd
  3. Apr 14, 2013 #2


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    Gold Member

    without comment on the correctness of your specific numbers, let me ask you this:

    Do you feel that I2 = 5m in the same sense that I1 = 1.43ma. That is, other than magnitude, would they have the same waveform if graphed?
  4. Apr 14, 2013 #3
    I guess I don't see what you're asking.
    This is a DC signal.

    For an AC signal, the would not have the same wave form due to the diode.
  5. Apr 14, 2013 #4


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    Gold Member

    Hm ... why do you suppose a DC source is labeled "Vin, VAC ?"
  6. Apr 15, 2013 #5
    Ignore the AC part, that's for another problem.
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