# When working with logic gates and transistors, which is more important to pass through them for them to work, a high current or a high voltage?

So I was wondering, if, say, I'm getting a current from a transformer where the current is very low but the voltage is very high. And there's a diode to turn my circuit into a DC circuit. And I'm using an AND gate to turn on my transistor.

For the gate, we need the two inputs to be high, but do we mean by the high input a high voltage or a high current. And to turn on the transistor do I need a high voltage or a high current or both?

I wrote this question in the physics community but I was kindly told that it should be posted here and that there are so many kind of different transisors but I was wondering what kind of transistors should I think of in my level (highschool igsce OL physics)

This confusion got into me when I was solving this question

and there were parallel and series connection—which contrary to normal questions where the high resistor would prevent a high voltage from reaching the other parts and it won't matter wether we think about voltage or current because they will always be low in the same time— here it was different. Even though it won't really matter which way I think about it here because in the end it's an AND gate but I still want to know.

PS: this isn't a hw question, I've the answers of the question already and understand how the circuit work, I'm just curious about how I should think about it.

• This question is really too broad; the best answer is probably read "The Art of Electronics" by Horowitz & Hill. Sep 11 '20 at 11:14