Now with 2 LEDs in series: (5V - 2.2V - 2.2V)/.02A = 30 ohm
2 Green, Yellow, Blue, Orange, etc. may have too much Vf for 5V to turn them both on, with Vf being 2.7V to 3.2V to 3.5V.
Am I right to assume that in this case, since there is not enough voltage, nothing will happen?
So, if I understand correctly, if i have 2 red LEDs in series, I will still need a 30 ohm resistor?