 Hello everyone, welcome to a video lecture on registers which are connected in series. Myself, K.R. Biradar, Assistant Professor, Department of Electronics and Telecommunication Engineering, Vulture Institute of Technology, Sholapur. Let us start with the learning outcomes first. At the end of this session, you will be able to justify the circuit behavior when registers are connected in series. Registers which are in series, when two or more registers are connected such that their one end is connected to another end, then they are said to be in series. The registers could be simple registers or bulbs or heating elements etc. The registers are measured in ohm and the symbol is used is shown here. Consider there are three registers R1, R2 and R3 are connected in series. The total or effective resistance of three registers R1, R2, R3 is given by Rs is the total or effective resistance is equal to R1 plus R2 plus R3. This is a circuit diagram or a network having three registers which are connected in series. The registers are R1, R2, R3 which are connected in series and having a supply voltage of VV. The sign conventions are shown in the network. The current flowing in the entire circuit is I but the voltage across each resistance will be different. The voltage across R1 is V1, the voltage across R2 is V2 and voltage across R3 is V3. But the current in all the registers will be same I. This is the actual picture of practical registers which are connected in series. You can see here 1 kilo ohm, 2 kilo ohm and 3 kilo ohm are registers are connected in series and there is a supply voltage or battery is connected across these registers. Expressions for registers in series according to Ohm's law if same current is flowing through different registers of different values then the potential difference across each register must be different. That means, we have already seen the current in all the registers will be same but voltage will be different in different registers. Let V1, V2 and V3 with a potential difference are voltage drop across each of the registers R1, R2 and R3 respectively. Then we can write V1 equal to I R1, V2 equal to I R2 and V3 equal to I R3. But the total voltage V is equal to sum of voltages across each register. Therefore, V equal to V is a total supply voltage which is equal to sum of the voltage drop across each registers. V equal to V1 plus V2 plus V3. So, V1 already we have know I into R1 similarly V2 equal to I into R2 and V3 is I R3. Substitute those things I R1 plus I R2 plus I R3 which is equal to we take I common I into R1 plus R2 plus R3 which is also equal to I into RS where RS is a total R equivalent resistance. Its value is RS equal to R1 plus R2 plus R3. We can see the circuit where supply voltage and only one RS instead of connecting R1, R2, R3. So, the equivalent resistance RS is mentioned in the circuit the current flowing is I. When several resistance are connected in series the total or equivalent resistance is the sum of individual resistance. In general if n number of registers are connected in series therefore, RS equal to R1 plus R2 plus R3 etcetera or n. Let us see one example. Here there are three resistance R1, R2, R3 are connected in series. There is supply voltage of V there sign conventions you can see in the diagram. There equivalent resistance also you can see. So, the equivalent resistance will be RS. Here three resistances R1, R2, R3 are connected in series. The total or effective resistance RS equal to R1 plus R2 plus R3. Suppose we have R1 equal to 2 ohm and R2 equal to 3 ohm and R3 equal to 4 ohm supply voltage V is given 10 volt. Therefore, we can calculate the RS equal to 7 ohm because all the three resistances are connected in series. We can directly add those resistances 2 plus 3 plus 4 which is equal to 7 ohm in the network. So, here RS in the second equivalent circuit you can say RS equal to 7 ohm in this example. The current flowing is I supply voltage is also V. You can see one more example. Calculate the equivalent resistance for the circuit which is connected to 24 volt battery. And also find the potential difference across 4 ohm and 6 ohm resistors in the circuit. You can see this diagram there is a 24 volt battery is connected. There are two resistances R1 which is equal to 4 ohm and R2 which is equal to 6 ohm are connected in series. The current flowing across this network is I. We need to calculate the equivalent resistance or total resistance or effective resistance. And also potential difference across or voltage drop across 4 ohm and 6 ohm resistors. Since the resistances are connected in series the effective resistance in the circuit is equal to 4 plus 6. Directly get added the value equal to 10 ohm. Since these resistances are connected in series the effective resistance are equivalent resistance is greater than the individual resistance. The current I in the circuit equal to total voltage divided by equivalent resistance. That is also equal to voltage he has given 24 volt. So, equivalent resistance we have connected equivalent resistance 4 ohm and 6 ohm are in series. Their value we have found out is 10. So, the current in the circuit becomes equal to 2.4 ampere. Now, we shall find the voltage across 4 ohm resistor. V1 is the voltage across 4 ohm resistors V1 equal to I R1. Current is same, but V1 and V2 are different drops in different resistors when connected in series. V1 equal to I into R1. I equal to 2.4 ohm and R1 is 4 ohm which comes out to be 9.6 volt. Similarly, voltage across 6 ohm resistors V2 equal to I into R2. I is 2.4 into 6 ohm which is equal to 14.4 volt. Now, we shall see a multiple choice question on this series resistance. Equivalent resistance of the resistors connected in series is dash individual resistance. Pass the video and think and try to write your answer. The options are the equivalent resistance of the resistors connected in series is definitely greater than individual resistance because when resistance are connected in series the total resistance will get added. So, here second one is the answer. These are the references used to prepare the above PPP. Thank you.