19.2 Series Circuits

4 min readjune 25, 2024

Series circuits are the foundation of electrical systems. They connect components in a single path, allowing to flow through each element sequentially. Understanding series circuits is crucial for analyzing more complex electrical systems and troubleshooting common household circuits.

In series circuits, current remains constant while voltage divides among components. This concept is essential for designing circuits with specific voltage requirements and calculating dissipation in electrical devices. Mastering series circuits paves the way for comprehending parallel and complex circuit configurations.

Series Circuits

Analysis of series circuits

Top images from around the web for Analysis of series circuits
Top images from around the web for Analysis of series circuits
  • establishes the relationship between voltage (VV), current (II), and (RR) in a circuit as V=IRV = IR
    • Voltage measured in volts (V) represents the across a component
    • Current measured in amperes (A) represents the flow of through a component
    • Resistance measured in ohms (Ω\Omega) represents the opposition to current flow in a component
  • (ReqR_{eq}) in series circuits is the sum of individual resistances: Req=R1+R2+...+RnR_{eq} = R_1 + R_2 + ... + R_n
    • In series circuits, the current remains the same through all components as there is only one path for current to flow
    • The total voltage across a is equal to the sum of voltage drops across each individual component
  • Current and voltage in series circuits can be calculated using Ohm's law
    • Current is determined by dividing the total voltage by the equivalent resistance: I=VReqI = \frac{V}{R_{eq}}
    • Voltage drops across each component can be found using the current and individual resistances: V1=IR1V_1 = IR_1, V2=IR2V_2 = IR_2, etc.
  • Power dissipated in each component can be calculated using P=IVP = IV or P=I2RP = I^2R

Interpretation of circuit diagrams

  • Resistors in circuit diagrams are represented by zigzag lines with their resistance values labeled in ohms (Ω\Omega)
    • Example: a with a value of 100 Ω\Omega would be shown as a zigzag line with "100 Ω\Omega" next to it
  • Batteries are depicted as long and short parallel lines, with the longer line representing the positive terminal and the shorter line representing the negative terminal
    • The voltage of the battery is labeled in volts (V) next to the symbol
    • Example: a 9 V battery would have "9 V" written next to its symbol
  • Switches are shown as a line with a break, representing the ability to open or close the circuit
    • An open switch indicates that the circuit is broken and no current can flow
    • A closed switch indicates that the circuit is complete and current can flow through the components
  • Capacitors are represented by two parallel lines and store electric charge
    • The capacitance values are labeled in farads (F) next to the symbol
    • Example: a with a value of 10 microfarads would be shown as two parallel lines with "10 μ\muF" next to it
  • Circuit diagrams use standardized symbols to represent various components and their connections

Current and voltage in series circuits

  • In series circuits, the current remains the same through all components as there is only one path for the current to flow
    • The current is determined by the total voltage supplied by the battery and the equivalent resistance of the circuit
    • Example: if a 12 V battery is connected to a series circuit with an equivalent resistance of 4 Ω\Omega, the current through the circuit would be 3 A (I=12V4Ω=3AI = \frac{12 V}{4 \Omega} = 3 A)
  • The total voltage in a series circuit is equal to the sum of voltage drops across each individual component
    • Voltage drops across components depend on their individual resistances
      • Components with higher resistance will have larger voltage drops
      • Components with lower resistance will have smaller voltage drops
    • Example: in a series circuit with a 12 V battery and two resistors (6 Ω\Omega and 3 Ω\Omega), the across the 6 Ω\Omega resistor would be 8 V, and the voltage drop across the 3 Ω\Omega resistor would be 4 V
  • states that the sum of voltage drops in a series circuit equals the total voltage supplied by the battery: Vbattery=V1+V2+...+VnV_{battery} = V_1 + V_2 + ... + V_n
    • This law is a consequence of the conservation of energy principle
    • Example: in the previous example, the sum of voltage drops (8 V + 4 V) equals the total voltage supplied by the battery (12 V)

Key Terms to Review (14)

Capacitor: A capacitor is a passive electronic component that stores electrical energy in an electric field. It is composed of two conductors separated by an insulator and is used in various electrical and electronic circuits to block DC signals, filter signals, and store energy.
Circuit Diagram: A circuit diagram is a graphical representation of an electrical circuit, showing the interconnections and components that make up the circuit. It is a essential tool for understanding and analyzing the flow of electricity within a system.
Current: Current is the rate of flow of electric charge, or the amount of electric charge passing a given point per unit of time. It is a fundamental concept in the study of electricity and is essential to understanding topics such as Ohm's law, series circuits, and electric power.
Electric Charge: Electric charge is a fundamental property of matter that is the source of all electrical phenomena. It is a scalar quantity that can be either positive or negative, and it is the driving force behind the attraction and repulsion of charged particles.
Equivalent Resistance: Equivalent resistance is the single resistance value that can replace a network of resistors to produce the same current and voltage relationships as the original network. It is a fundamental concept in the analysis of electrical circuits, particularly in the context of series and parallel circuits.
Inductor: An inductor is a passive electronic component that is used to store energy in the form of a magnetic field. It is a crucial element in various electrical circuits, particularly in the context of series circuits and electric power applications.
Kirchhoff's Voltage Law: Kirchhoff's Voltage Law (KVL) is a fundamental principle in electrical circuit theory that states the algebraic sum of the voltage drops around any closed loop in an electrical circuit must be equal to zero. It is one of the two key laws, along with Kirchhoff's Current Law, that govern the behavior of electrical circuits.
Ohm's Law: Ohm's law is a fundamental principle in electrical engineering that describes the relationship between the voltage, current, and resistance in an electrical circuit. It states that the current flowing through a conductor is directly proportional to the voltage applied across it, and inversely proportional to the resistance of the circuit.
Potential Difference: Potential difference, also known as voltage, is the electrical potential energy difference between two points in an electrical circuit. It is the driving force that causes electric charge to flow through a conductor, such as a resistor or a wire, and is measured in volts (V).
Power: Power is the rate at which work is done or energy is transferred. It represents the amount of energy or work produced or consumed per unit of time. This concept is fundamental to understanding various physical phenomena and their applications across different fields, including mechanics, electricity, and simple machines.
Resistance: Resistance is a measure of the opposition to the flow of electric current in a circuit. It is a fundamental concept in electrical engineering and physics, as it determines the amount of current that can flow through a given component or circuit under an applied voltage.
Resistor: A resistor is a passive electronic component that is used to control or limit the flow of electric current in a circuit. It is a fundamental building block of electronic circuits, playing a crucial role in various topics, including Ohm's law, series circuits, parallel circuits, and electric power.
Series Circuit: A series circuit is an electrical circuit in which components are connected end-to-end in a single loop, allowing only one path for the flow of electric current. The current is the same through each component in the series, and the total voltage across the circuit is the sum of the voltages across each individual component.
Voltage Drop: Voltage drop is the decrease in electrical potential that occurs when current flows through a resistive component, such as a wire, a resistor, or any other electrical device. It is a fundamental concept in understanding the behavior of electrical circuits.
© 2024 Fiveable Inc. All rights reserved.
AP® and SAT® are trademarks registered by the College Board, which is not affiliated with, and does not endorse this website.