I've seen lots of videos on resistors, but they all calculate voltage drop after multiple resistors. Let's say I have a series circuit, with a 12 volt battery bank and a 8 ohm resistor, nothing else in the circuit. If I use ohms law to find the amperage (12/8 which means the amperage is 1.5 amps), then multiply amps by total resistance (which is 8), I get, of course, 12 volts. Is that the voltage after the resistor or the voltage drop, and why is it the same amount as the input?