Types and Components of Electric Circuits

Types of Circuits

There are different types of electric circuits; each one has its advantages and can be used for a specific purpose. One distinction comes from the direction of the flow of current, as with AC and DC circuits.

DC Circuits

Direct current or DC circuit is characterized by the flow of current in one direction. It is commonly found in low-voltage applications and is usually powered by a battery. A simple circuit containing a lightbulb, a switch, and a battery is an example of a DC circuit. As shown in the direction of the arrows in the diagram below, current flows in only one direction.

Charges flow in one direction in a DC circuit.

DC circuits are also categorized into two types based on how the components are connected. These two types are parallel and series circuits.

Parallel Circuit

A parallel circuit has two or more separate paths for the current to flow,. Electrical connections found at home and most commercial establishments are in parallel. In this type of connection, the rest of the circuit still works even if one device is disconnected.

A parallel connection is characterized by two or more separate branches for the current to flow.

When different loads, such as light bulbs or resistors, are connected in parallel, the voltage across each load is the same. Since it is composed of several paths, the total current in the circuit is the sum of the individual currents passing through each load.

Series Circuit

A series circuit is characterized by a single path for the current to flow. In this type of connection, the electrical components are connected end to end, as shown in the diagram. Since there is only one path, the current that flows in one load (e.g., light bulb or resistor) is the same amount of current that passes through the other loads. The total voltage in the circuit is the sum of the individual voltages in each load.

A series circuit is distinguished by a single path for the current to flow.

Water heaters, freezers, and refrigerators employ a series circuit to control the temperature of the device. Once the desired temperature is reached, the circuit automatically opens and stops the flow of current.

AC Circuits

An alternating current or AC circuit is characterized by a periodic reversal of the current's direction. The changing current then varies the value of the voltage as it fluctuates between a negative and a positive value in line with the changes in the current. A fluorescent lamp, for example, whose power supply has a frequency of 120 Hz, would flicker 120 times per second. This fluctuation is so rapid that it would be difficult for the eyes to detect.

Power distributions use AC circuits, so most households and commercial establishments employ this type of circuit. Note that electricity is generated by large power-generation plants, and requires transmission through long distances to reach individual users. To achieve this with minimal power losses, high voltages from power plants are transmitted then reduced to smaller values once it reaches the user. The increase and decrease of voltages are much easier to accomplish in AC circuits than in DC, which is why AC is more commonly used in large power distributions.

Large power distributions use AC circuits.

Components of Electric Circuit

What are the three components of a circuit? The basic components of electric circuits include a voltage source, a load, and a conductive pathway.

• A voltage source is an electrical component that supplies energy. It provides a potential difference for the charges to flow. Examples of voltage sources are a battery and a generator.
• The load in a circuit is a device that uses electrical energy. A load can be a resistor, a light bulb, or a motor.
• A conductive pathway provides a path for the current to flow and is used to connect the electrical components to each other and the power source.

The three basic components of an electric circuits.

Besides these three basic elements, most electrical circuits also employ a switch to easily turn on or off the circuit. Other common passive electrical components are resistors, capacitors, and inductors.

• Resistors provide a specific value of resistance in a circuit. Its primary function is to limit the flow of current and can be used to divide the voltage and/or adjust signal levels.
• Capacitors are used to store electric charge temporarily when connected to a voltage source. It resists any change in voltage and stores energy in the form of an electric field. It has a wide range of applications, from electrical signal filtering, to motor starter, and to defibrillator — a device used to deliver an electric shock to a patient's heart when an abnormal heartbeat occurs.
• Inductors are also used to store charge, but unlike capacitors, it resists changes in current and stores energy as a magnetic field. Some of its applications include tuning circuits and proximity sensors.

Some circuits contain the following three passive components: resistor, capacitor and inductor.

How Do Electric Circuits Work?

A simple DC circuit helps show how an electric circuit works. For it to work, the circuit should be closed and all components should be connected to each other and to the voltage source. The voltage produces a potential difference that allows the current to flow. It is essential to note that a voltage source does not supply charges to a circuit, it only provides a potential difference to make charges that are already present in the wires and other electrical components move. By convention, the current's direction is similar to how positive charges move, which is from the positive terminal to the negative terminal of the battery. It is called the conventional flow of current and is opposite to the real direction that electrons follow. Once the circuit is closed, the charges in the circuit — both in the wires and the filament — to move, making the lightbulb lit up. Any break in the circuit would cause the charges to stop moving, resulting in an unlit light bulb.

Current flow in a DC circuit and an AC circuit

The current in a circuit can be compared to how water flows in a hose connected to a pump. As long as the hose is connected to a pump and the height of both ends of the hose differs, water will flow. The pump is similar to the potential difference supplied by the battery or any voltage source. Note that the water is already present in the hose, similar to how charges are already in the electrical components itself.

AC circuits use the same principle as DC circuits. However, instead of charges moving in one direction, charges simply move back and forth in a periodic motion, as a result of the periodic reversal of the voltage.

Lesson Summary

An electric circuit is composed of electrical components that form a continuous conducting path connected to the terminals of a power source. The basic components of electric circuits are voltage source (such as a battery), load, and conductive pathway. A voltage source provides the potential difference needed for the load (e.g., resistor, lightbulb). The conductive pathway connects all the electrical components. Other passive components in an electric circuit include resistors, capacitors, and inductors. Resistors limit the amount of current that passes in the circuit. Capacitors store energy as an electric field. It stores energy and releases it in a single burst. Inductors, on the other hand, store energy in the form of a magnetic field.

The types of electrical circuits based on the current's direction are direct current and alternating current. Direct current or DC circuits are characterized by the flow of current in a single direction, while alternating current or AC circuits have periodic reversals of the current direction. The DC circuit is also categorized into two — series and parallel. Series circuits consist of only one path for the current to flow, while parallel circuits are composed of two or more branches or paths.