Well sort of -
I was making the assumption the the element is a 3.7 watt element
I see you point as to the resistance having to be variable.
The question is - is it
Take this example a 60 watt light bulb running at 110 volt requires
0.54545 amps current draw
Same 60 watt blub ran at 12 volts
5 amps
Did the resisance Change ?
Is it Liner? A light bulb is a just a coil too?
Granted I see your point that if you look at the resistance side of the coin it is pulling more amps (current) BUT if it is current limited by the wattage wouldn't the resistance have to change and the the current would be lower.?
No, your logic is flawed. Heat dissipated by resistors is determined by the voltage difference on leads unless current flowing through it is limited.
Using ohm's law current flowing through the coil is 5/3.7=1.3514 amps. 5*1.3514=6.7570 watts, or just 5^2/3.7=6.7570 watts.
You can pull 500mA from usb port and since it gives 5v you can pull max 5*0.5=2.5000 watts of power from it. Again using ohm's law 5^2/x=2.5 and solving x gives 5^2/2.5=10 ohms. So atomizer coil would have to have resistance of 10ohms to pull max allowed amount of power from usb bus.
Just to check, 5/10=0.50000 amps.
I should have said the power or wattage of the coil is 3.7 Watts NOT Resistance. Resistance of the coil is ALSO 3.7 ohms but will decrease as the voltage will go up also because the coil only needs 3.7 Watts to operate.
