Re: does resistance reduce voltage or just ampera
E= 'electromotive force'... the 'v' stands for volt which is the unit used to measure EMF... the formula isn't V = A • ? even though it would make 'sense' from a direct reading 'volts = amps • ohms'. I forget why current is 'i', probably after the guy who discovered it /ubbthreads/images/graemlins/wink.gif
back to topic... in a series circuit the voltage on all the components adds up to the voltage of the source so adding things in will reduce the voltage on all the other parts (even if it's just one.... led)... the higher the resistance the more voltage will be dropped on that particular component... inserting a series resistance will increase the 'total' resistance which will reduce the 'total' current going through the resistor and the led, which is the goal.
another forumula that is key is P=IE... power = current • voltage... once you have a resistor figured out... run that formula to figure out how much power is being consumed by the resistor (turned into heat) because you need a resistor tough enough not to melt... (example: 1/4W, 1/2W, 1W(very big).
have fun, most importantly.
-awr