Say, I have this circuit (please ignore the zeros, and the diode should be some load that draws 10ua):
So, V_in be 12V. I would say that D1 gets R2/(R2+R1)*12V as voltage. Then, as I know that it draws 10ua, the resistance there should be 12V /10ua = 1,200,000. Then, the resistance for D1 plus R2 should be 1/(1/1,200,000 + 1/R2). If I add this up with R1 since they are in series, I get the total resistance.
So, is the total current in this circuit according to Ohm's law: 12V / (R1 + 1/(1/1,200,000 + 1/R2) ? If not, where am I wrong?