So Ohm's law says I=V/R pretty simple, say I had a 5 volt source and a load I wanted to limit to 20 mA, so I would use a 250 ohm resistor which would limit the current to 20 mA at 5 volts. (I'm correct so far right?) (And presumably if the device tried to draw more the voltage would drop right?)
Now the calculation for an LED is R = Vsource - Vled/I.
So the equation is, simple if I want to power an LED with a forward voltage of 3.4v(which is basically the voltage the LED requires right? Sort of like my phone requires 5v? Not sure if Im understanding this) And a maximum current of 20ma then I would need an 80 Ohm resistor.
But then what would that make in the voltage that you're dividing (the V or Vsource-Vled in in ohms law, or the top of the fraction), the voltage you want to drop across resistor?
No that couldn't be right. The voltage going through the resistor?
As you can tell I'm a little confused and I might just misunderstanding this completely.
Also say I want the power to of those LEDs in series with one 5 volt source, how would I calculate that?