Check my answer for a question regarding Thevenin Theorem

Discussion in 'Homework Help' started by Ashenrise, May 12, 2016.

  1. Ashenrise

    Thread Starter New Member

    May 2, 2016
    2
    0
    This is exactly how my professor formatted the question:
    For the circuit shown below, calculate:
    (a) Thevenin Voltage (Vth)
    (b) Thevenin Resistance Rth
    (c) Load current ( IL )

    this is what I got but I'm not sure what I'm doing wrong:

    Vt= 10.9V - 0.9 V= 10 V

    1. Vth= R2xVt/(R2+R1)

    2. Vth= 600 x 10/600+400= 6000/1000= 6 V

    3. Rth= R1+R2= 400+600= 1kohm

    4. IL= Vth/RL+Rth= 6/1+1= 3mA
     
  2. HW-nut

    Member

    May 12, 2016
    45
    11
    From your drawing, I am not exactly sure where the load is looking into, so I’m going to assume that the load is R3.

    Vth = V1 – V2 = 10V

    And Vth = R1+ R2 = 1K

    IL = Vth / (Rth + RL) = 10/ (1K + 1K) = 5 mA

    Hope this helps.
     
    Last edited: May 12, 2016
    Ashenrise likes this.
  3. HW-nut

    Member

    May 12, 2016
    45
    11
    Whoops, not supposed to answer the question. Let’s try this again.

    From your drawing, I am not exactly sure where the load is looking into, so I’m going to assume that the load is R3.

    Vth is the open circuit voltage, What is the voltage at R3 if R3 is removed from the circuit?

    Rth is the output resistance, what is the resistance across R3 if R3 is removed and the voltage sources are shorted?

    Determining the load current should be straightforward once the circuit is redrawn in Theveninequivalent form.
     
    Ashenrise likes this.
  4. Ashenrise

    Thread Starter New Member

    May 2, 2016
    2
    0
    I understand now, thanks so much, I used multisim to check it again and your answers were there, I don't know why I didn't get it the first time. Anyway, I appreciate the help greatly.
     
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