1. The problem statement, all variables and given/known data This is just one of the example problems in my book which is already solved for me, but I don't really understand their solution which I'll post here: They start out with assuming Vin is very negative, which makes D1 turn on and makes Vout=VD,on+Vin. THen they solve for the currents. 2. Relevant equations KCL/KVL 3. The attempt at a solution What I am confused on is that if the diode is turned on, then the branch with the diode is a short circuit, so why is there current going in the R2 branch? The book solves all the problems like this one the same way, but I don't really get it. Are we assuming the diode is actually on the brink of turning on/off, so it allows current through it, but it's actually not a short circuit yet?