Resistors in Series

Resistors in Series
Resistors in Series

Resistors in series are vital to electrical circuits. Series-connected resistors follow the same current path. Analyzing and developing circuits requires understanding resistor behavior in this connection. Engineers and technicians can calculate series circuit resistance, voltage division, and power dissipation using this idea. This topic helps students comprehend circuit behavior and acquire circuit analysis and design skills.

1. Resistors defined

Resistors are passive electronic components that block electric current in electrical circuits. Usually constructed of carbon or metal alloys, they are resistant. Resistors control circuit current by converting electrical energy into heat. Resistors, measured in ohms (Ω), are classified as fixed, variable, or special, each fulfilling distinct circuit design functions. Working with resistors in series requires knowledge of their properties.

1.2. Series link explanation

Two or more resistors linked end-to-end produce a single current route in a series connection. Since there is no alternative way for current to diverge, each resistor in a series circuit receives the same current. The voltage across each resistor depends on its resistance. The overall circuit voltage is the sum of all series resistor voltages. Circuit analysis requires understanding series connections to calculate current flow, voltage division, and overall resistance.

Resistors in Series
Resistors in Series

You undoubtedly know how resistors control electric current in circuits. Did you aware that series resistors add resistance? Calculating series circuit total resistance can help you understand how voltage and power are distributed across each component. This article describes how to calculate series circuit total resistance step-by-step. With an example calculation, you’ll learn how the formula works, why total resistance is critical for circuit analysis, and how to use voltage division to calculate resistor voltage drops. We’ll also discuss series circuit power dissipation and how to avoid overheating. This is the place to learn how series resistors act. Jump in!

What are series resistors?

When resistors are connected in series, their resistances accumulate to determine circuit resistance. Add the resistor resistances to calculate the series circuit’s total resistance (RT):


Using three resistors of 10 Ω, 15 Ω, and 20 Ω in series yields the total resistance:

RT = 10 Ω + 15 Ω + 20 Ω = 45 Ω

The circuit’s current flow at a given voltage depends on the overall resistance. Higher overall resistance lowers current.

Each resistor in a series circuit has the same current, but its voltage depends on its resistance. This is voltage division. Calculate Vn for any resistor:

Vn = Rn/RT x Vs

Total circuit supply voltage is Vs. If three resistors (10 Ω, 15 Ω, 20 Ω) are connected in series with a 12V supply, the voltage across each would be:

V10 Ω = (10 Ω/45 Ω) x 12 V = 2.67 V V15 Ω = (15 Ω/45 Ω) x 12 V = 4 V V20 Ω = (20 Ω/45 Ω) x 12 V = 5.33 V

All resistor voltages add up to supply voltage:

2.67 V + 4 V + 5.33 V = 12 V

Voltage division helps circuit analysis and design. Choose resistor values to control circuit component voltage.

Heat is dissipated by resistors. Calculate each series resistor’s power consumption:

P = I2 x R(V/RT)2

Current through the resistor is I and voltage across it is V. Knowing each resistor’s power dissipation helps prevent overheating, which can damage the resistor or circuit.

Calculating Series Resistor Total Resistance

In a series circuit with numerous resistors, sum their resistance values to calculate overall resistance. Just that simple!

Before completing the circuit, current must flow via each series resistor. The overall resistance equals the sum of the resistors because they all pass the same current.

Three resistors in series with values of 10, 15, and 20 ohms yield the total resistance:

10 + 15 + 20 = 45 ohms

Total resistance is 45 ohms. Simple, right? Using Ohm’s law, you can determine circuit current from total resistance. The source voltage distributes across each resistor based on overall resistance.

When reducing voltage or power in increments, series resistors are utilized. The voltage drop across each resistor depends on its relative resistance to the whole. Most voltage drops across a resistor with a high resistance relative to the total. Voltage division is essential to series circuits.

In summary, to find series circuit total resistance:

List each resistor’s resistance.

Total the resistance values

Total series circuit resistance is sum.

Keep these steps in mind to calculate total resistance appropriately every time. Resistors in series look basic, but total resistance and voltage division bring up new circuit design possibilities!

Series Resistors Voltage Division

Resistance increases when resistors are joined in series. In a series circuit, add the resistor resistance values to determine the total resistance (RT):


Using three resistors in series with values of 50 Ω, 100 Ω, and 150 Ω results in a total resistance of 300 Ω.

Total resistance matters for several reasons. Ohm’s law (I = V/R) is used to compute the circuit’s total current (I). The total current via all series resistors is the same.

Second, total resistance lets you calculate voltage drop across each resistor using voltage division. In proportion to resistor resistance, supply voltage divides. In the example above, a 300 Ω total RT and 9 V supply voltage result in 5 V across the 50 Ω resistor, 3 V across the 100 Ω resistor, and 1 V across the 150 Ω resistor.

Finally, using P = IV, you can compute power dissipation in each resistor based on voltage. Choosing resistor kinds and sizes that can handle your circuit’s power without overheating requires considering heat dissipation.

Although resistors in series look easy, understanding total resistance, voltage division, and power dissipation across several resistors helps you design more sophisticated circuits and understand current, voltage, and power flow. Walk through some instances to grasp these fundamentals.

Resistor Power Dissipation in Series Circuits

In series, resistors’ resistances add up to generate the circuit’s resistance. This total resistance affects series circuit current.

Total Resistance Calculation

Add the resistances of series resistors to determine their total resistance (RT):


Using three resistors of 10Ω, 20Ω, and 30Ω in series yields the total resistance:

RT = 10Ω + 20Ω + 30Ω = 60Ω

Total resistance regulates how much current flows through the series circuit based on Ohm’s Law (I=V/R). Given the same voltage, higher total resistance reduces current flow while lower total resistance increases it.

Series Circuit Voltage Division

Resistors share the voltage in a series circuit. The voltage across each resistor depends on its relative resistance to the whole. Higher resistance resistors receive more voltage.

In a 12V series circuit with two resistors (10Ω and 20Ω), the total resistance is 30Ω. As the 10Ω resistor has 1/3 of the total resistance, it receives 1/3 of the entire voltage (4V). Due to its 2/3 resistance, the 20Ω resistor receives 2/3 of the entire voltage (8V).

This voltage division method is useful when you want to drop most of the voltage over a single series resistor or disperse it in a certain ratio across numerous resistors. Use the voltage division formula to calculate resistor voltage:

V = R/RT x Vtotal

V is the voltage across one resistor, Vtotal is the circuit’s total voltage, R is one resistor’s resistance, and RT is the total resistance.

Applications and Importance of Series Resistors

The circuit’s resistance is the sum of series-connected resistors. Total resistance impacts circuit current, therefore this is vital to understand.

Total Resistance Calculation

To compute the total resistance (RT) of series resistors, add their resistances:

RT = R1+R2+R3+…

The total resistance of three resistors of 10 Ω, 20 Ω, and 30 Ω in series is:

RT = 10 Ω + 20 Ω + 30 Ω = 60 Ω

The cumulative resistance always exceeds the individual resistances. The series circuit will draw less current than if each resistor were connected individually. Applications and Importance

Knowing a series circuit’s overall resistance lets you calculate its current and voltage drop across each resistor. This information is essential for circuit design and troubleshooting.

For example, using Ohm’s equation (I=V/R), a 120 V power source linked to a 60 Ω series circuit will result in 2 A of current flow. Using the voltage division concept, you can calculate that 40 V drops across the 30 Ω resistor, 24 V across the 20 Ω, and 16 V across the 10 Ω.

In conclusion, calculating the total resistance of series resistors helps you examine the circuit and assure adequate current flow. This prevents resistors from overheating or other circuit components from being underpowered. Understand this concept and you’ll be a resistor series circuit pro in no time!


Everything you need to know about total resistance and series circuit voltage division is here. Resistors are essential circuit components; therefore, electronics enthusiasts must understand how they work in series. Formulas and calculations may seem hard, but with practice solving examples, you’ll calculate total resistance and voltage losses quickly. After learning the basics, you can apply them to more sophisticated circuits. First focus on resistor in series, then build up. Happy calculating!

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