Misunderstanding about the choices of current values in KCL equation

 By KCL,
-ID2 + (-I2) = 0

0 = ID2 + I2

Q1: Do you think this equation is correct? (i assume it is correct because it came from my professor's notes)

Q2: Which node do you think this equation is used for making this equation with  values currents which is going in and out to the selected partcular node? (I would guess node at V2 but why the input current will be 0 according to 0 = ID2 + I2?)

Q3: why will my professor choose this node? (to be honest, i have no clue. I will ask my professor later but want to see your opinion.)

Hi,

First, I don't see the point in having KCL at V2. You are using DC supply, simply looking at it no current will flow at D2 since it can't be biased or this is considered open. The only current here is the ID1 and IR1kΩ.

Thank you Kevin for answering.

Q1: Is that the triangle symbol at the top with 5V means DC supply?

I understood that D2 should be off so it can't be biased and is considered as open circuit.

but I was going thought some calculations with Constant Voltage Drop Model.

Q2: What is the clue to just simply looking at it can let you understand D2 has no current?