I have a 16ma 9volt current source which I connected 3 LEDs to in series. I measured the current flowing through the positive terminal and it was 12ma. Next I connected 3 LEDs to separate 16ma 9volt current source. I measured the total current and found it to be 48ma. All the LED brightness were very similar.
I am assuming that the brightness is a function of power (watts) and that as the power increases, either the voltage or the current must go up. If the voltage stays the same (9 volts) and the current increases by a factor of 3, then the power (total LED brightness) must increase by a factor of 3. However, this is not the case. Maybe there is a heat factor that I am not considering.
How can 15ma illuminate 3 LEDs in series as brightly as 36ma can illuminate 3 LEDs in parallel?