Minimum Resistance Calculation

Minimum Resistance Calculation

So if you have a LED that should be powered by 3.2v and 0.024 amps, and a 9v battery, the calculation should be:

(9 - 3.2) / 0.024

And that gives you 240 ohms


Bonus : Watts Calculation

If you want to calculate the watts of this LED (which is actually the power it will consume) you have to do this:

Power (watts) = Voltage * Current (amps)

So:

Power = 3.2 * 0.024 = 0.0768 W