So, am doing this question paper for my electronics, and I stumble across a question that asks me to calculate the current through a diode, with a breakdown voltage of 1.7, an Imax current of 20ma, when the diode is hooked up to a resistor of unknown value (calculated on a further question). There are 5 pairs of these LED's/resistors in parallel by the way, but only asks me to calculate the voltage of one diode. My intuition told my to subtract 1.7V from 9V, which would enable me to calculate currents and resistances. I was right. However this is only due to previous experience where I got it wrong.
I don't understand WHY we don't include the forward voltage drop, surely that's part of the overall resistance, as V=R*I and the diode cannot conduct until it reaches 1.7V due to the resistance faced by the PN junction... so, wouldn't excluding the fact that 1.7V is being dropped due to the PN band at the diode lead to false results?