I am asking for a fundamental and physical explanation of why, not formulas.
Let's take an ideal resistor. Let's say I have some voltage source not big enough to breakdown and destroy the diode, but much larger than its threshold voltage of .7 V; whether this is a good value or not, let's say 5 V.
I have this 5 V AC source in series with a diode in forward bias and no other circuit components.
Physically, what is stopping the full 5 V from developing across the diode in forward bias but the not reverse bias?
I am thinking of the ideal diode graph where during the positive half of the cycle the voltage is Vd (0.7 V) and during the negative half -5 V. I can't understand or find a reason for this.
Most of the answers are that the current limits the voltage or that after 0.7 V there is no more ability for the diode to develop more than 0.7 V drop.
Why is it able to in reverse bias but not forward bias?
After I apply so much voltage beyond 0.7V, the resistance drops so more current flows, which doesn't seem to make sense to me.
So somehow in forward bias this device magically limits the voltage to some threshold, but also if apply more voltage the resistance keeps dropping to allow more current. I have to be missing something here. I want to understand the actual why. A lot of analogies were to that of a valve, it only has an opening so big, so more pressure (voltage) will cause more water (current) to flow through. I still just don't get how the voltage is self limited like this.