Video instructions and help with filling out and completing Will Form 2220 Reduced

Instructions and Help about Will Form 2220 Reduced

So some guy comes up to you in a dark alley and he says hey kid you want a dollar and you say sure aneesa's will get me the current going through every one of these resistors and so he draws the following circuit diagram for you there's a resistor there and then there's this funky point right here it doesn't look so funky yet but he's just dropping sisters all over the place and you know it's gonna be a long evening but you've only got 15 minutes to solve the AP problem so you'd better get working I mean the problem posed by the strange guy on the street who's gonna give you a dollar if you get it right we got resistors all over the place so this is our first picture of this circuit diagram and he starts giving you some numbers turns out he's a pretty nice guy you talk about his kids everything's fine there's a 12 volt battery powering this circuit and he wants to know what current and I'm gonna choose myself a color here he wants current through each thing and voltage across each resistor so that's the language that we use the current goes through a resistor and the voltage is across a resistor voltmeters would come on here like like this I'll just draw you a voltmeter here's the voltmeter that comes on here and you would connect like that Casilla voltmeter an ideal voltmeter has infinite resistance and no current given the choice the currents coming out here the currents like oh I see infinite resistance or some finite resistance chooses to go through the resistor an ammeter is the opposite sort of thing an ammeter right here would actually excuse me an ammeter would be in line with there we go it's an anarchy meter no just kidding it's an ammeter and the currents going through the ammeter now ideally the ammeter has no resistance at all so I should draw this ammeter green to try to stay with my with my program there the ammeter will log the resistance through this nasty nasty nasty lead wrong resistor let's see if I can clean up this resistor a little bit and it would give us the current going through that resistor there so here's the procedure let's make this thing a real problem by giving you all kinds of resistor values this one he says is 68 ohms and this one he says is 5 ohms he wants this one to be 12 ohms I don't know where he's getting it getting these because these are not standard resistances but somehow he managed to get all of these 30 ohms set up this problem yourself so that you can also do this and pause me whenever I get ahead of you but I'm going to use equivalent resistances to find the overall resistance this is my battle plan I'm going to find the overall resistance of the circuit and then I'm gonna say hey if I've got a voltage and I've got some resistance over here I'm much currently going through the circuit as a whole and then I'll notice that that current is present here and it goes through this resistor so the overall current will go through this one and it will come back and go through that one and get back into the battery but you see the current Forks right here it's got three different paths that it can take so this is going to be a little bit complicated but my intention is to solve the entire problem with V is IR and equivalent resistances in parallel and in series so this is series equivalent resistance is r1 plus r2 plus r3 etc and for parallel I know that 1 over the equivalent resistance is the sum of the inverses of the individual resistances and we will play with those so that you get a feel for how this pattern works okay my plan is to use these three simple relationships to solve the entire problem and to do it I'm going to keep track of which sheets I'm working on and I'm going to ultimately come back to this sheet and fill in every bit of information V I and R for each resistor given the resistances all right so I want to simplify this this messy thing right here and I'm planning to draw it just a little bit differently I want to draw myself a battery and a resistor right here and then you see I've got these three paths in my three paths that I have right here so I'm gonna take down right here and then bring it back well shoot there's a resistor right here sorry this is a little bit sloppy I'm gonna try to do a little bit better next time now this intersection here it's got three of them so I'm gonna draw a one coming out here and then down that way and the third one is going to be over here and that way and then that way and then back do you see how that is the same map as what we've already done so now I label these guys this is picture two by the way but we've got 68 ohms and five ohms and 30 ohms and five and five ohms and this suckers 12 ohms and that sucker there is 12 volts now I first need to recognize before I actually simplify it that was just cleaning it up I first need to recognize what is the combination of resistors that I can analyze first it looks like these three resistors are in series but they're not because there's something in parallel with it it looks like these two resistors are in parallel but they're not because there's something else in parallel with them in addition it looks like these three are in parallel with each