About Passive Components: Resistor, Capacitor, and Inductor | New Topic [2024]

In this note, we are discussing about some Passive Components like Resistors, Capacitors, and Inductors. Welcome to Poly Notes Hub, a leading destination for Diploma Engineering Notes for Engineering Students.

Author Name: Arun Paul.

What are Passive Components ?

Passive components in electrical and electronics refer to elements or devices that don’t require an external power source to operate or amplify electrical signals.

Examples: Resistors, Capacitors, Inductors, etc.

About Resistors

A resistor is an electronic component that is designed to introduce resistance or create an opposition to the electric current in an electrical circuit. Its primary function is to limit or control the flow of electric current. Resistors are made of materials that impede the flow of electricity, thereby reducing the amount of current that can pass through them. They are widely used in electronic circuits to manage voltage levels, control currents, set specific values in circuits, and prevent damage to components by limiting the flow of electricity. Resistor values are measured in ohms (Ω), and they come in various types, sizes, and power ratings to suit different applications in electronics.

What is Resistance ?

It is the property of a material by which it opposes the flow of electric current through the material. In the context of electricity, resistance is measured in ohms and is denoted by the symbol “Ω”. It’s a fundamental property in electrical circuits, dictating how much a material or component impedes the flow of electrical current.

The resistance in a material is determined by factors like its dimensions, the material it’s made of, and its temperature. For instance, metals typically have low resistance and conduct electricity well, while insulators have high resistance and impede the flow of electricity.

Types of Resistors

The resistors are classified in to two groups –

1. Fixed Resistors
2. Variable Resistors

The Fixed Resistors are classified as follows –

1. Carbon Composition Resistors.
2. Thin Film Resistors.
3. Thick Film Resistors.

The Variable Resistors are of Two Types –

1. Carbon Composition
2. Wire Wound

Applications

Below, we listed some applications of Resistors –

1. Electronic Circuits: They are fundamental in electronics for controlling current flow, setting voltage levels, and dividing voltages in circuits.
2. Voltage Division: Resistors are used in voltage dividers to obtain a fraction of an input voltage, crucial in sensors, analog circuits, and signal processing.
3. Current Limiting: They help limit the current in circuits, preventing damage to components and ensuring safe operation.
4. Signal Processing: Resistors are used in filters, amplifiers, and signal conditioning circuits to modify signals and achieve specific outcomes.
5. Voltage Regulation: In power supplies and voltage regulators, resistors help stabilize and regulate voltage levels.

About Capacitors

An electric field is created by storing and releasing electrical energy through the use of a capacitor, a passive electronic component. It is made up of two conductive plates divided by a dielectric, which is an insulating substance. The capacitor stores energy when there is a voltage differential between the plates because the dielectric creates an electric field.

The many types, sizes, and capacitance values of capacitors influence how much charge they can hold. Although practical capacitors often have capacitance values in microfarads (μF), nanofarads (nF), or picofarads (pF), the capacitance of a capacitor is measured in farads (F).

What is Capacitance ?

The capacitance of a condenser is the property at which it deposits a quantity of electricity between two conducting plates. It is denoted by the letter ‘C’. The unit of the capacitance of a condenser is farad and denoted by the letter “F”. It is an S.I. unit. The capacitance is also said to be as the charge of the capacitor per unit voltage applied.

Types of Capacitors

There are various kinds of capacitors based on their application and different kinds of factors –

1. Ceramic Capacitors
2. Electrolytic Capacitors
3. Film Capacitors
4. Variable Capacitors
5. Tantalum Capacitors
6. Electric Double Layer Capacitors

Applications

Capacitors are used in different kinds of Electrical and Electronics equipment like –

1. Power Supply Filtering: Capacitors smooth out voltage variations and filter unwanted noise in power supplies, ensuring stable and clean power delivery to electronic devices.
2. Coupling and Decoupling: They enable AC signals to pass while blocking DC signals, coupling different stages of amplifiers and decoupling noisy signals from power sources.
3. Energy Storage and Backup: Capacitors store electrical energy and release it when needed, serving as backup power sources in systems like cameras’ flash units or in memory backup circuits.
4. Timing Circuits and Oscillators: They play a crucial role in timing circuits and oscillators, determining the frequency of oscillation in electronic devices like clocks or microcontrollers.
5. Signal Processing: Capacitors are used in filters to allow specific frequencies to pass through while attenuating others, essential in audio circuits, radio frequency (RF) circuits, and telecommunications.

About Inductors

An inductor is an electrical component that stores energy in a magnetic field when an electric current passes through it. It’s typically made of a coil of wire wound around a core material such as iron, ferrite, or air.

When current flows through the coil, a magnetic field is generated around it. The strength of this magnetic field is directly proportional to the amount of current passing through the inductor. When the current changes, the magnetic field also changes, and this change induces a voltage, resisting any change in the current flowing through it. This property is often referred to as inductance.

What is Inductance ?

When an electric current flows through a coil, a magnetic field or flux is created and the electrical energy is stored in the form of magnetic field. The inductance is the property of a coil by virtue which it opposes any change in current in it . The unit of inductance is Henry(H). When there is any change of current (either increase or decrease)in the coil the magnetic flux linked by the coil itself also change .

Types of Inductors

There are various types of inductors based on their application and different kinds of factors –

1. Air Core Inductors
2. Ferromagnetic Core Inductors
3. Toroidal Inductors
4. Variable Inductors
5. Multi Layer Inductors
6. Couple Inductors

Applications

Below we listed some important applications of Inductor –

1. Oscillators and Tuned Circuits: Inductors are used in oscillators and tuned circuits to select specific frequencies and create oscillations. They’re employed in radios, telecommunication devices, and signal processing circuits.
2. Power Conversion: In power electronics, inductors are used in DC-DC converters and switching power supplies to regulate and store energy, enabling efficient voltage regulation and current control.
3. Magnetic Storage Systems: Inductors are integral in magnetic storage systems like hard disk drives, where they play a role in reading and writing data by controlling magnetic fields.
4. Motor Control and Electrical Equipment: Inductors are used in motors, generators, and various electrical equipment for controlling current, reducing voltage spikes, and regulating power flow.
5. Radio Frequency (RF) Circuits: They’re employed in RF circuits for impedance matching, tuning antennas, and creating resonant circuits in wireless communication devices.