And, if there are more than one resistance, okay, then it depends on whether they are in parallel or in series, okay? The current can be described similarly, okay? So, in, let's just for the fun, for this simple one. In this case, if the resistances are in series, then the current is equal to, this big R is equal to R1 + R2. Okay, great. And then, there's another important component which we call capacitor. And, the capacitor is another essential component of the electrical circuit, okay? And, how do we describe the current going through the capacitor in a circuit? Okay. Again, it's very simple, okay? The capacitor needs time to get in charge okay? So initially, when this circuit was on, okay, there is no charge across the capacitor okay. The current will be the biggest, okay? And then, over time, the capacitor will get charged, okay? And, that would generate a voltage across this capacitor, okay? Which, in turn, will lower the driving force and amount of current to charge this capacitor. Okay, and eventually when this capacitor is fully charged, it will have the same voltage across this battery, the same. And, the net current in the circuit is going to be zero. We are going to look at that inside a neuron, and see, what is the relevance for this simple Ohm's Law in the capacitors, okay? So, this describes the same thing, if you have the resistance in the capacitors again initially if you look at the time. Initially, how will the current change. The current will become lower and lower because, initially the capacitor is not charged, this capacitor is as if it does not exist, all the current will go through to charge it. And the current is only determined by the resistance in this case. But once the capacitor is getting charged and charged, the current goes down in a exponential fashion, lower and lower, okay? How do we do that, to study the membrane of a neuron? Well, a cell membrane can be thought of a composition of special resistances and capacitors and it's just their combination, whether it's in series or in parallel. And again, we mentioned Sir Hodgkin and Huxley who make the most fundamental contribution using a special animal squid, giant squid, okay? And in fact, many neuroscientists worshipped these two great neurophysiologists, okay? So especially, they not only illustrates the mechanism of action potential, they are great experimentalists. They generated their, or they modified their own apparatus instruments to do those measurements. Till this day, some labs are still using the micromanipulator designed by Andrew Huxley, okay? That can make fine movement of the electrode, okay?