Get this full course at http://www.MathTutorDVD.com. In this lesson you will learn about power analysis in AC circuit analysis. Here we discuss Reactive power with an inductive Load. We will learn how the energy from the circuit is stored in the magnetic field of the inductor and later in the cycle the energy is extracted from the magnetic field. The student will learn the difference between real and reactive power. We will also discuss how reactive power is involved in power factor calculations. ----------------------- hello welcome to this lesson in AC circuit analysis. the title of this lesson is called reactive power with an inductive load so we're going to talk about the concept of reactive power here and we're going to be talking about the concept when that applies to having an inductor inside of the load. and the last section we had just a resistive Network just resistors and we talked to in great detail about what's going on with the power when we just have resistors so if you haven't watched that section go back and watch it and you to reacquaint yourself what's happening with resistive Network is we have an a nonzero average we have an average amount of power delivered to that resistor and the it's it's oscillating the instantaneous power. is oscillating up and down but it's always positive and so there's always an average value when you have a resistive Network here we'll talk about what happens we have inductive loads the next section we'll talk about what happens we have capacitive loads really excited to teach this because up until now we talk about resistors everyone can wrap your brain around resistors right because resistors are kind of the easiest thing to understand circuits they obey Ohm's law is equal to IR and you have some kind of familiarity with with what's going to happen when the sinusoids go up and down and things are in phase you. know the current the voltage are in phase so it's kind of even though there was a lot of math in the last section it was very easy to follow i think if you watch it enough times and study it enough times what's really happening with a resistor but when you have inductors and when you have capacitor suddenly the current and the voltage across those things are no longer in phase and things get a little bit murky so we're going to take it slow we're not doing problems are going to theory for the next few sections and when you get to your problems you'll understand these terms you'll understand what's really happening so let's revisit this is what I call the granddaddy power equation i'm going to leave it on the board for very for a great many sections its instantaneous power so if you start the stopwatch and time marches on this is the time dependence here this is a constant term these this is the time dependence you stick in the numbers with your phase angles for the current the voltage which is going to be governed by your circuit that you have and this is going to be some kind of sinusoid overtime and it's telling you that the instantaneous power is always changing but we want to zero in on the case when we have just an inductive load what's going to happen when there's just an end. after inside the box last section we talked about what happens when there's a capacitor in the box now we're going to talk about if the load is purely inductive what happens and i can tell you right now actually it's something really cool that happens and I i find this stuff really fascinated with circuit analysis so this is some of the reasons i'm really excited about teaching it right the first thing you need to remember there's very very few things I tell you in circuit theory to just remember right one of them's Ohm's law is equal to IR right you have to know that some of the real basic power equations just memorize them what I'm going to tell you here is something you should just remember when you have a purely inductive load all right the current ok crossing through that inductor lags the voltage by 90 degrees exactly the current lags the voltage and an inductor or across an inductor by exactly 90 degrees current lags the voltage by 90 degrees i'm going to show you how to prove that to yourself but just remember it because if you can just remember it that these few little things I tell you to remember it's going to make your life so much easier so let's go down here and write that down and I'll explain what i'm talking about the current lags the voltage by I'm gonna put the word exactly 90 degrees and i'll give you a hint when we get two capacitors it's also going to be 90 degrees but the current is not gonna lag the voltage a capacitor the current will lead the voltage by 90 degrees so the 90 degrees part is going to be easy to remember the leading versus the lagging is what always confused me when.