Resistors in Series – Complete Guide

Resistor, the most basic yet essential passive component of an electronic circuit, is nothing but a device that restricts the flow of current. So why is it called passive? It is called so because it dissipates power rather than generating it in a circuit. Some practical resistors are shown in figure 1.   The figure 1 (above image) shows how they look in reality, but obviously there will be some schematic way of representing it in a circuit. Usually, in a circuit diagram you see a component denoted by zigzag lines, which look like that shown in figure 2 (below image); that component is a resistor.  If you are interested to know in-depth about resistors, our article titled” Resistors and type of resistors” will help you.   Since resistors obey Ohms law and Kirchhoff’s circuit laws, they are used to convert voltage into current and vice versa. This means by manipulating the value of resistor we can change either of them(voltage or current). But, how can the resistance in a circuit be manipulated? Do we have to choose different resistor of another value each time we have to change the voltage/current? This sounds like a tedious task, so is there any simpler method to change the resistance of a circuit? Yes, there is! Actually, the resistors can just be connected together to form complex resistor networks, that have an effective change in the total resistance of the circuit. They can be wired either in series or in parallel or a combination of both and be replaced by a single equivalent resistor. Therefore, instead of choosing a different resistor every time you want to change it in the circuit, you can just add the available resistors to connect them in series, parallel or combination of both.  This article will help you understand the resistors in series. How are resistors connected in series? In order to understand the connection of the resistors in series, let us take two resistors namely R1 and R2. Let R1 have terminals a1 and b1, and R2 have terminals a2 and b2 (See figure 3)   Now, if we connect the terminal b1 of resistor R1 and terminal a2 of terminal R2, we would get a daisy chained type resistor network. (See Figure 4) This is how resistors in series look like when they are connected. Also we can add more resistors in the same fashion. These daisy-chained resistors can be represented as a single resistor, having an effective resistance, Reff. This replacement of series resistors by a single resistor doesn’t change the overall current/voltage.       Ohm’s law in a series resistor circuit: Let us take three resistors, R1, R2,­ R3  ,connected in series, having an equivalent resistance of Reff, having a voltage of V applied across them, as shown in fig, 7. Let I be total the current that flows through the circuit.   Then according to ohms law: V α I That is, V= R­eff I  ……..(1) From the eq 1, it is quite clear how changing the effective resistance would change the current, I of the circuit. Next, we need to know how to calculate the effective resistance, for this, first let us see what changes it brings to Voltage and Current, in the circuit. Voltage and current in a series resistor circuit: To understand how connecting resistors in series affects the current and voltage, let us assume the following: V1 , I1 = Voltage and current through resistor R1. V2, I2 = Voltage and current through resistor R2. V3,I3 = Voltage and current through resistor R­3. V, I = Total voltage...
read more

The post Resistors in Series – Complete Guide appeared first on Electronic Circuits and Diagram-Electronics Projects and Design.