Voltage divider loaded

Jony130

Joined Feb 17, 2009
5,598
Try to think in terms of current flow in this circuit, and when it begins to split.



Now notice that at node A the I1 current splits into two individual currents I2 and I3. And at node C the currents join again into one current I1 = I2 + I3.
So to find VA voltage we need to find equiv resistances.
Rt = (R2 + R3)||RL2 = 2.126kΩ
And we can find VA voltage using ohms law and Kirchhoff's laws.
Itot = 35V/(R1 + Rt) = 10.5mA and VA = 35V - Itot*R1 = 22.4V
Now notice that Rs = R2 + R3 and RL2 are connect in parallel.
And this means that V1 = V2 = VA = 22.4V
So
I2 = VA/(R2 + R3) = 22.4V/3.7kΩ = 6.05mA
I3 = VA/RL2 = 22.4V/5kΩ = 4.48mA

And finally VB = I2 * R3 = 6mA*0.7kΩ = 4.23V
I hope you see know that I2 current don't splits into other branches.
And this is why we can use this VB = VA * R3/(R2 + R3).
 

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Thread Starter

Random3s

Joined Jul 30, 2014
38
Thanks for persevering Jony, I really appreciate your efforts here, and you have made all of this much clearer for me. I think I need to get along with some examples now.

Thanks again!
 
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