Passive components in electronics: definitions and applications (2024)

In the field of electronics, passive devices are electronic components that do not require an external energy supply. These devices are typically used for functions such as signal transmission, conditioning, and processing in circuits. Passive devices are opposed to active devices, which require external energy to operate. This article will explore the definition, common types, working principles, and application areas of passive components.

Definition of passive components
Passive devices are components in electronic circuits that do not actively generate energy. They have no energy source of their own and cannot amplify or control current or voltage. Passive components can only achieve circuit functions by changing the transmission characteristics of current or voltage. Passive devices are characterized by passively responding to input signals from a circuit without actively generating signals.

Common types of passive components

1. Resistor

Resistors are one of the most common passive components used to limit the flow of current or divide voltage. It is usually made of conductive material and has a fixed resistance value. Resistors limit current flow by converting electrical energy into heat. In circuits, resistors are widely used in functions such as current regulation, voltage division, and signal attenuation.

2. Capacitor
Capacitor is a common passive device used to store electric charge and store electrical energy. It is separated by an insulating medium between two conductors, creating an electric field. When a capacitor receives an electric current, equal but opposite charges accumulate on the positive and negative terminals. Capacitors are used in circuits for a variety of applications such as signal filtering, adjusting signal frequency, and storing electrical energy.

3. Sensor
An inductor is a passive device that converts electrical energy into magnetic energy or mechanical energy. It is based on Faraday's law of electromagnetic induction, which induces voltage or current by transforming the magnetic field. Inductors include coils, inductors, transformers, etc. They are commonly used in electronic devices for applications such as filtering, isolation, sensing, and energy conversion.

4. Magnetic materials
Magnetic materials are a special type of passive devices that have the ability to attract and generate magnetic fields. Magnetic materials can be divided into soft magnetic materials and hard magnetic materials. Soft magnetic materials have high magnetic permeability and low residual magnetism and are often used in devices such as inductors and transformers. Hard magnetic materials have high remanence and coercive force and are used to manufacture magnets and permanent magnet devices.

5. Transistor
A transistor is a semiconductor passive device mainly used to perform functions such as signal amplification, switching and regulation. Typically, a transistor consists of three or more electrodes, including a base, emitter, and collector. Its working principle is based on the input signal to control the output current or voltage. Transistors are widely used in electronic devices, including amplifiers, computer chips, and logic gates.

How passive components work

Passive devices are devices that do not amplify, amplify or generate electrical signals in a circuit. Here are some common passive components and how they work:

1. Resistor
Resistors convert electrical energy into heat through resistance within the material, thereby limiting the flow of current or dividing voltage. The resistance value of a resistor is determined by parameters such as the material's conductivity, cross-sectional area, and length.

2. Capacitor
Capacitors store charge and energy through an insulating medium between two conductors. When a capacitor receives a current, equal but opposite charges accumulate on the positive and negative terminals. The stored energy of a capacitor is related to the capacitance value of the medium, voltage and plate area.

3. Sensor
Inductors utilize Faraday's law of electromagnetic induction to induce voltage or current by transforming the magnetic field. When the coil or conductor in the inductor is subjected to changes in the magnetic field, an induced electromotive force is generated. The output voltage or current of the inductor is related to the magnetic field change rate, the number of turns of the coil and the magnetic permeability of the material.

4. Magnetic materials
Magnetic materials have the property of attracting and generating magnetic fields. Soft magnetic materials can effectively conduct magnetism in alternating magnetic fields and are often used in devices such as inductors and transformers. Hard magnetic materials can generate long-lasting magnetic fields and are often used in applications such as manufacturing magnets and permanent magnet devices.

5. Transistor
A transistor is a semiconductor passive device that regulates output current or voltage by controlling an input signal. It consists of three or more electrodes, including base, emitter and collector. The working principle of a transistor involves the electronic behavior of semiconductor materials, such as the control of the pn junction and gate between N-type and P-type semiconductors.

These passive devices play a key role in the electronics field, providing necessary functionality for a variety of applications. Whether it's current limiting, signal conditioning or energy conversion, passive
Devices all play an important role in enabling modern electronic devices and circuits to function properly.

Passive devices have a wide range of applications, including but not limited to the following:

1. Communication system: Resistors, capacitors and inductors are used for signal conditioning, filtering and isolation in wireless communication systems to ensure stable signal transmission.

2. Power management: Capacitors and inductors are used in power management circuits to store energy and stabilize voltage to ensure the stability of the power supply system.

3. Sensing technology: Sensors are widely used to measure physical quantities such as temperature, pressure, humidity, speed, etc., and are used to monitor and control various systems.

4. Audio and video equipment: Resistors and capacitors are used in audio amplifiers and video processors to provide high-quality sound and images.

5. Medical equipment: Passive components are used in medical equipment for vital sign monitoring, imaging and treatment to ensure the accuracy and safety of medical procedures.

6. Automotive electronics: Capacitors and inductors are used in automotive electronic systems for engine control, airbags and entertainment systems to improve vehicle performance and comfort.

7. Industrial automation: Sensors and magnetic materials are widely used in industrial automation for robot control, production line monitoring and sensor networks.

8. Energy management: Sensors and magnetic materials are used in energy generation and conversion, including solar cells, wind turbines and transformers.

In short, passive components are indispensable components in the electronic field. They provide critical functions for various circuits and devices. By understanding the different types and working principles of these passive components, electronic engineers and technicians are better able to design and maintain modern electronic systems to meet the needs of different applications. The continuous development and innovation of these devices will also continue to promote the progress of electronic technology and bring more convenience and benefits to our life and work

Passive components in electronics: definitions and applications (2024)
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