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Series and Parallel DC Circuits; Equivalent Resistance

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Terms you will need

  • series circuitA series circuit is a type of electrical circuit where components are connected one after another, so the same current flows through each component.
  • parallel circuitA parallel circuit is a type of electrical circuit where components are connected in separate paths, so each component has the same voltage across it, but the current can split and flow through different paths.
  • equivalent resistanceEquivalent resistance is the total resistance of a combination of resistors in a circuit, whether they are connected in series, in parallel, or in a mix of both.
  • ohmAn ohm is the unit of electrical resistance, which measures how much a material resists the flow of electric current.
  • voltA volt is the unit of electrical voltage, which measures the electric potential difference between two points in a circuit.
  • ampereAn ampere is the unit of electric current, which measures the amount of electric charge flowing through a circuit per second.

How this topic runs

  1. 1Start here
  2. 2How it works

Series and parallel DC circuits are fundamental to understanding how electrical components interact in a circuit. In a series circuit, resistors are connected end-to-end, so the same current flows through each resistor, but the voltage is divided among them. In a parallel circuit, resistors are connected across the same two points, so each resistor has the same voltage, but the current is divided among them. The total resistance in a series circuit is simply the sum of the individual resistances, while in a parallel circuit, the reciprocal of the total resistance is the sum of the reciprocals of the individual resistances. Understanding these configurations is essential for analyzing and designing electrical systems, from simple lighting circuits to complex electronic devices.

Figures (4)

A series circuit with a voltage source (such as a battery, or in this case a cell) and three resistance units
A diagram of several resistors, side by side, both leads of each connected to the same wires.
A diagram of several inductors, side by side, both leads of each connected to the same wires.
A diagram of several capacitors, side by side, both leads of each connected to the same wires.

Series and parallel DC circuits are ways to connect resistors in a circuit. The total resistance in a parallel circuit is found by adding the reciprocals of each resistor and then taking the reciprocal of that sum. This means the total resistance in a parallel circuit is always less than the smallest individual resistor.

To picture this, imagine a series circuit as a single path where water flows through several narrow pipes in a row. Each narrow pipe adds to the total resistance, making it harder for water to flow. In a parallel circuit, imagine multiple paths for water to flow, each with its own narrow pipe.

The water splits into these paths, and each path has the same pressure (voltage), but the total resistance is lower because there are more paths for the water to take. Understanding these configurations helps in analyzing how current and voltage behave in different parts of a circuit. Series circuits are used when you want components to share the same current, while parallel circuits are used when you want components to share the same voltage.

Key Points

  • A series circuit is a circuit composed solely of components connected in series, where the same current flows through all of them and the voltage drop is the sum of the individual voltage drops across each component.
  • A parallel circuit is a circuit composed solely of components connected in parallel, where each component has the same voltage across it and the total current is the sum of the currents flowing through each component.
  • Equivalent resistance is the total resistance of a combination of resistors, calculated by reducing the resistors in series and parallel to a single resistance that has the same effect on the circuit as the original combination.

Terms

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Sources & licensing(4)