# Offset diode model

I am trying to see if diode1 and diode2 is off or on.

I assumed off/ on . I tried to do node analysis in Vo to figure out Vo.

But I don't know the current flowing in blue circled branch in the picture.

My professor just assumed that the current flowing in that branch is 0.

Why is the current flowing through the blue branch zero?

$V_O$ is the open-circuit output voltage. It is all you are asked for in this case so you don't need to worry about current in that branch. It makes the solving the problem much simpler as now you only have to calculate the voltages.
• Finish your calculation for $V_O$ as shown in your second photo.
• Then think what happens when the diodes are replace (a) if $V_O > 0$ in the previous step and (b) if $V_O < 0$.