 Welcome again to one of the different experiment that we are going to perform using real components. The experiment is based on the verification of K V L. Now what is K V L? You all know that K V L is Kirchhoff's voltage loop, which is very much resemble with the voltage division loop. What has Kirchhoff's told about K V L? He said that, K V L states that The total voltage is the algebraic sum of the various voltage drop taking place across the loop. Now, when I say across the loop, let me explain it with using the circuit. You are seeing in this circuit, this is a circuit used for KVL. Now, this is a circuit having a source, three resistance in series. So, KVL says that this total voltage will be equal to the voltage drop across each of these resistances. So, we can calculate this total voltage using a multimeter as a voltmeter connecting it across the source. Similarly, we can use another multimeter as a voltmeter and connecting it across the resistor. Same way R2 connecting it across the resistor, we are using one more voltmeter. And similarly for R3, we are using one more voltmeter to connect across Rthian, calculate the voltage. So, in this way we can calculate the total voltage as well as the individual voltage drop across the three resistances. So, we have implemented this circuit on the breadboard, connected all these things together and I am just now going to show you the different values. I guess you are very much familiar with the orientation of the breadboard. So, I am not going to show you how you are going to connect the components. So, let us come from this circuit to the real circuit. So, I am closing this one and now coming back to the real circuit, do not look this side, this is just come to this before this yellow line. This is the circuit of this KVL. We have a voltage source of this, you can see. This is the dual power supply. Here I have used one of the section of the dual power supply and giving a voltage of 12 volt. So, you are all familiar with dual power supply. So, I am using one section giving a 12 volt. These two are connected with the circuit. So, I was showing you the source in the circuit that is this source, 12 volt. Now, forget about this. 12 source is there coming back in the circuit. In this circuit that is connected to 12 volt, this is the first register, this is the second register and this is the third register. We have all three register connected in series. Now, I am going to use one different multimeter as a voltmeter. Now, how to use multimeter as a voltmeter? You just have to keep this knob in this range. When you say this range, this is the range to start from 200 millivolts, 2 volts, 20 volts, 200 volts, 600 volts. But you can see this is Vm. So, this will give you a DC voltage. When you are calculating DC voltages, you always keep your knob in this range. Now, as I am kept my range of this multimeter in this, so this became a voltmeter. In the voltmeter, now this is connected to the source. Source means what you actually supply. From here, you are supplying 12 volt and here in the voltmeter, as this is a multimeter being used as a voltmeter, is showing 11.96. There is a small voltage drop because of this all wires we are using. So, wires have resistance. I already explained, so this thing shows a voltage drop because resistance, across a resistance, when a current flows, there is a voltage drop. The same concept we are going to use in this circuit. So, there are different resistances R1, R2, R3. Let us see what is a voltage drop across R1. I am taking this red one and this black one and connecting it across the resistor. You can see on the multimeters some value are appearing. Focus on that, it is 1.49, right? Yeah, it is 1.49, right? So, 1.49 is the voltage drop across the R1. So, let me take a page and explain in the page about the circuit. The same circuit is here. The circuit voltage source R1, R2, R3 and I am connecting different terminals to show that this are calculating the voltage drops. So, I am saying this V will be equal to the individual voltage drop that is V1 plus V2 plus V3. And how this V1 comes? Obviously, the current in this circuit is the same. Current is same, but voltage at every point is different. So, as the current is same, I am saying this first V1 voltage that is across the R1 will be equal to current into, you all know Ohm's law is very V equal to IR. So, V is equal to I into R. I is the total current, R1 is the resistance of that particular component. Similarly, V2 is I into R2, V3 is I into R3. So, we got this expression from this KVL, applying KVL in this loop. This is called a loop and in this loop the current is I. So, first I calculated how much was the voltage if you remember that was in across R1 was 1.49 volts. So, I am writing down that. I am again adding up it with the second voltage I am calculating using it, multimeter is connecting across the second resistor. I am getting around 3.55 you can see in the emitter. It is showing 3.55. So, I am writing down there for the second one V2 3.55 volt. That will be added up with the voltage drop across the third resistor. So, this is the third resistor. I am using the multimeter to connect it across the third resistor and to see the voltage drop. And you can see in the multimeter the voltage drop showing a 6.80. So, I am writing that 6.80 here volts. And I sum up all. When I sum up all this is how much 1.49 I can show it to be 1.5. This is 3.5. So, 1.5 across 3.5 this become 5 volts. And this is 6.8. So, it is approximately is becoming 11.7 something, 7.5 anything I am getting an approximation I am not taking the exact one. So, this is coming 11.75 volts. So, you are getting what your V was equal to how much V was equal to 11.96 volts which is equal to 11.75 volts. Again, why this small drop is there? This we call denoted by approximation sign this. This is the approximation sign I will draw it with a sine wave. This is the approximation sign that 11.96 is approximately equal to 11.75. This proves your KVL which of voltage load that the total applied voltage will be equal to this sum of the voltage drop across the various resistances connected in series. So, this is how 11.96 in the input that was getting in the input was equal to the sum of various drops across the output. So, this is how we prove our KVL. So, if you want to calculate theoretically what is V1 I will show you in the page V1 that is this V1. This across this V1 will be equal to the total voltage V you have applied into the resistance in which you are searching a voltage drop that is R1 divided by the total resistances that is R1 plus R2 plus R3. So, I am writing R1 plus R2 plus R3. This is how we are going to get the theoretical value. This V1 is equal to total voltage into R1 by R1 plus R2 plus R3. So, this is a theoretical value you may be getting some value. I am not calculating this is your job to do it. So, after calculating this value you will see that this V1 when you are calculating practical I am writing here let me show you. This was theoretically calculate I know you calculated. When I calculate V1 practically I found V1 to be around 1.49 volts. So, this theoretical value which you will be getting and this practical value will vary a little bit because theoretically we do not consider the resistance of the connecting wires. So, connecting wires do have resistances. So, theoretically we do not consider that but practically the current consider it. So, when you consider it practically there is a voltage drop across those wires also. So, that is the reason why the difference between the theoretical value and practical value comes. So, this is how we prove our KVL. I hope you liked the video. Thank you for watching it.