Hello! I'm still not clear on a few things: For example: Let's say a manufacturer creates a device which runs at 120W (let's say a lightbulb). Does this mean that i can use which combination of voltage and current such that V*I=120W i want? Another example: Let's say that the maximum voltage across a capacitor is 300v. Can i run it with as high current as i want as long as i don't exceed 300v? My second question is that instead of adding resistors to decrease current can't we just add a transformer instead which will decrease voltage to produce the same current? Thank you for answering!