Author Options:

resitance equation for Led's? Answered

Could you show me how you got the 300ohms from your example above? I have a feeling it has something to do with decimal places but I am not sure how. I got a value of .3



11 days ago

the rated current of the led is in milliamps but the equation requires current in amps so you have to convert 20 milliamps to amps 20 / 1000 = 0.02
(9 - 3) / 0.02 = 300 ohm