What is Resistance? Unit | Types of Resistance | New Topic [2024]

In this note, we are discussing about a topic called What is Resistance property of an electrical element. Also about the Unit of Resistance and Types of Resistance as well. Welcome to Poly Notes Hub, a leading destination for Diploma Engineering Notes for Polytechnic Students.

Author Name: Arun Paul.

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 Resistance

The resistance is classified into three categories from the point of measurement –

1. Low Resistance – One Ohm or less.
2. Medium Resistance – Above one ohm and upto 10⁵ ohm.
3. High Resistance – 10⁵ ohm and above.

What is Resistor ?

A resistor is an electronic component specifically designed to introduce resistance into 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.

Types of Resistor

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.
6. Temperature Sensors: Certain resistors change resistance with temperature, making them useful as temperature sensors in various applications.
7. LEDs and Display Panels: They’re used to limit current flowing through LEDs, ensuring they don’t receive excessive current and get damaged.
8. Audio Equipment: In audio circuits, resistors are used for volume control, signal shaping, and impedance matching.
9. Instruments and Measurement: Precision resistors are used in instruments and measurement devices for accuracy in resistance values.
10. Industrial and Automotive Applications: In automation, control systems, and automotive electronics, resistors play vital roles in circuitry for control, sensing, and safety.