Introduction to the basic knowledge and parameters of resistance, an important component of electrical fundamentals

In physics, resistance is a fundamental physical quantity that refers to the degree to which a conductor obstructs the passage of current through it. The unit of resistance is ohms (Ω), defined as the ratio of the voltage across a conductor to the current passing through it. Resistors are ubiquitous in our daily lives, from simple circuit components to complex electronic devices, all of which rely on the presence of resistors. This article will introduce you to the basic knowledge and parameters of resistance, helping you better understand this important physical concept

1、 Types of resistors

According to the magnitude and properties of resistance, resistance can be divided into the following categories:

1. Fixed resistor: a resistor with a constant resistance value, such as carbon rod resistor, metal wire resistor, etc

2. Variable resistor: A resistor whose resistance value can be adjusted within a certain range, such as a sliding resistor, varistor, etc

3. Thermistor: A resistor whose resistance value changes with temperature, such as NTC thermistor, PTC thermistor, etc

4. Photoresistor: A resistor whose resistance value changes with the intensity of light, such as a photoresistor, photodiode, etc

5. Potentiometer: a component that can adjust voltage or current, actually a variable resistor

2、 Parameters of resistance

In order to more accurately describe the performance of resistors, we need to introduce some parameters to measure the characteristics of resistors. Here are some commonly used resistance parameters:

1. Resistance: The value indicated on a resistor, indicating the degree to which the resistor obstructs the current. The unit is ohms (Ω)

2. Power: The maximum power that a resistor can withstand. The unit is watts (W)

3. Current density: The current passing through a unit area. The unit is Ampere per square centimeter (A/cm2)

4. Voltage drop: The decrease in voltage generated when current passes through a resistor. The unit is volts (V)

5. Power loss: Due to energy loss inside the resistor, the difference between the actual output power and the input power. The unit is watts (W)

6. Response time: The time it takes for a resistor to respond to external stimuli. The unit is seconds (s)

3、 Application of resistors

Due to its important role in circuits, resistors are widely used in various electronic devices and circuits. Here are some common examples of resistor applications:

1. Power filtering: Using high-power resistors to filter the power supply, making it more stable

2. Current limiting protection: Adding appropriate resistors to the circuit to limit excessive current flow

3. Voltage divider: uses series resistors to achieve voltage division

4. Constant current source: By adjusting the resistance value, the current in the circuit is kept constant

5. Sensor: Using photosensitive, thermosensitive, pressure-sensitive and other resistors as sensors to detect various parameters in the environment

Resistance, as an important component of electrical fundamentals, is of great significance for us to understand and master circuit principles. This article aims to help you better understand the basic knowledge and parameter introduction of resistors, and provide reference for your learning and practice