 In this video, we're going to be discussing a parallel resistive circuit. So we're going to look at what happens to the voltages across all the branches here. We're also going to look at what the individual currents are through each branch. And then we're going to sum up the video by discussing how you can take all these currents to determine what the overall current is and use that to determine what the overall resistance is. And then we'll look at another way of calculating out the resistance total as well. Getting started here, you notice that we have 100 volts as a source. Well, when resistors are in parallel, you've got the same. Remember that the voltage law states that the voltage across parallel branches will always be the same. So we've got 100 volts across each branch here. Very easy to calculate. Then we can use Ohm's law to calculate what the current is through each branch just by going 100 volts divided by 20 Ohms will give us the current for that branch. 100 volts divided by 40 Ohms will give us the current for that branch. And then on and on we go. So here we have 10 divided by 20 equals 5 amps. 100 divided by 40 equals 2.5 amps. 100 divided by 50 equals 2 amps. 100 divided by 25 equals 4 amps. So now we have the current that is running through each branch and currents running from negative deposit there to there through there and through there as well. So what we're going to decide or not decide but determined to do now is figure out what is our overall current going in this circuit, circulating in the circuit. And what we have to remember there is that the law of current states that the current entering a node has got to be the same as exiting a node. And what we're going to do is just add all these currents up. So we're going to add 5 plus 2.5 plus 2 plus 4 to get what our total current is here. So we end up with 13.5 amps, which means we start out with 13.5 amps. We drop off 5 amps there. We keep going. We drop off 2.5 amps there. We keep going. We drop off 2 amps there. We keep going. We drop off 4 amps there. Then we pick up those 2 amps. We pick up those 2.5 amps and we pick up those 5 amps and we end up with 13.5 amps on that side. Now to calculate our total resistance in the circuit, we have each individual branch. That's easy enough. But to get our total circuit resistance, the easiest way to do it again is using Ohm's law. 100 volts divided by 13.5 amps will give us our total resistance, which is 7.4 Ohms. Which is fairly easy to calculate, but there's another way to do it as well. We could use the law of resistors in parallel and we could take them and we could go 1 over 20. Remember because we have to add them reciprocally. 1 over 20 plus 1 over 40 plus 1 over 50 plus 1 over 25 gives us 1 over the answer. So there we go. 1 over 20 plus 1 over 40 plus 1 over 50 plus 1 over 25 gives us 1 over resistive total. So just calculating that out in the calculator for you. 1 over 20 is the same as 0.05. 1 over 40 is the same as 0.025. 1 over 50 or 1 over 50 is 0.02 plus 0.04. So you add all those up and you get an answer of 1 over 0.135. That's where people make mistakes because oftentimes they'll see students come back and give me an answer of 0.135 but you've got to reciprocate that answer there. So we've got to hit the 1 over button on our calculator or go 1 divided by 0.135 and that gives us the answer of 7.4 Ohms. So you can calculate it both ways. That's what I like about these circuits is there's more than one way to do it. So there's a way to go back and check your work. So that's it. So remember the rules for a parallel branch circuit resistive. Voltage remains the same. Current splits. You'd add all the currents up to get your total current. You can take your total voltage divided by your total current to get your total resistance or you could add the reciprocals of the resistors to get the overall resistance and do not forget to flip that last answer. It's 1 over RT, not RT.