What Does A Resistor Do? A Complete Guide

If you’ve ever tinkered with electronics, you’ve likely come across resistors – small, unassuming components that play a crucial role in controlling electrical current flow. But what exactly do they do, and how can you choose the right resistor for your project?

In this article, we’ll dive into the function of resistors, explore the different types available on the market, and provide tips for selecting the right resistor to ensure your circuits run smoothly. Whether you’re a seasoned DIY electronics enthusiast or just starting out, read on to learn all about these essential components.

What Does a Resistor Do?

Resistors are an essential component of electronic devices, but many people may not know exactly what they do or how they work. In this article, we will explore the function of resistors, the different types available, and how to choose the right resistor for your projects.

The function of a Resistor

At its most basic level, a resistor is a passive two-terminal electrical component that resists the flow of electrical current. This resistance is measured in ohms (Ω) and can be calculated using Ohm’s law:

Resistance = Voltage / Current

The higher the resistance value, the more it limits the flow of electrical current. This is important because in many electronic circuits, it is necessary to reduce or control the amount of current flowing through certain components.

For example, if too much current flows through an LED (light-emitting diode), it can burn out quickly. By adding a resistor in series with the LED, you can limit the current flow and prevent damage.

Resistors are also commonly used to set biasing points in transistors and amplifier circuits. They can regulate voltage levels and protect sensitive components from damage due to overvoltage.

Types of Resistors

There are several types of resistors available for use in electronic circuits. The most common type is fixed resistors, which have a set resistance value that cannot be adjusted. These come in various shapes and sizes such as axial leaded resistors (cylindrical shape), surface-mount resistors (rectangular shape), and wire-wound resistors (coil-shaped).

Another type of resistor is a variable resistor or potentiometer. These allow you to adjust their resistance by turning a knob or sliding a lever. They are often used for volume controls on audio equipment or as variable voltage dividers in circuits.

Thermistors are another type of resistor that changes their resistance value based on temperature variations. They can be used as temperature sensors or for regulating temperature-sensitive components such as motors.

Other less common types include photoresistors (resistance changes based on light intensity) and varistors (resistance decreases when voltage increases).

Choosing the Right Resistor

When choosing a resistor for your project, there are several factors to consider:

  • Resistance value: Make sure you choose a resistor with the correct resistance value for your circuit.
  • Power rating: Resistors generate heat when conducting electricity so make sure you select one with an appropriate power rating that won’t overheat.
  • Tolerance: This refers to how close the actual resistance value is to its rated value – usually expressed as a percentage.
  • Temperature coefficient: Some resistors change their resistance values depending on temperature fluctuations so make sure you choose one with an appropriate coefficient for your application.

There are online tools available that can help you calculate these values and choose the right resistor for your project.

You can Also Use Our Resistor Color Code Calculator and get the results in a few seconds!


In conclusion, resistors play an important role in electronic devices by controlling or limiting electrical current flow. There are several types available including fixed, variable, thermistors, photoresistors, and varistors – each with their own specific properties and uses.

When selecting a resistor for your projects make sure to consider factors such as resistance value, power rating, tolerance and temperature coefficient. Understanding these concepts will allow you to build more efficient circuits while protecting valuable components from damage due to overvoltage or overheating issues.


What are 3 purposes of a resistor?

There are many purposes of a resistor, but three common ones are to limit current flow, control voltage levels, and protect sensitive components from damage.

Why do we use resistors in a circuit?

We use resistors in a circuit to regulate the flow of electrical current or voltage levels. They can also be used to set biasing points, protect components from overvoltage, and act as temperature sensors.

What is a resistor and how does it work?

A resistor is an electronic component that resists the flow of electrical current. It works by reducing the amount of current that flows through a circuit by converting some of the electrical energy into heat.

Does resistor reduce current or voltage?

A resistor reduces current flow in a circuit by limiting the amount of electricity that can pass through it. However, if the resistance value is too high, it can also reduce voltage levels as well.

Leave a Comment