 Most electronic products have resistors. Companies that manufacture electronic products and appliances usually source resistors from other manufacturers and assemble them in their products.

Are you planning to buy resistors? Read on the article to the end. We are going to give you a full guide about resistors.

## What is a Resistor?

Resistors resist the flow of current in an electronic circuit. They also resist the change in voltage within a circuit. The resistor comes with different resistances, typically measured in Ohms (Ω).

Probably you have heard about Ohms law. This law states that the voltage passing through resistors in a circuit is directly proportional to the current.

Resistance changes according to the material resistors are made out of.

From this law, you will understand the importance of resistors. They play a vital role in all electronic circuits.

Resistors resist the flow of current in an electronic circuit. They also resist the change in voltage within a circuit. The resistor comes with different resistances, typically measured in Ohms (Ω).

## How do resistors work?

To understand the working of resistors, let’s consider a resistor with resistance (R) connected at its two terminals and connected through some voltage source (V).

Initially, when we turn on the DC power supply, there is no current flowing in the circuit. This means that charge carriers are not passing through the resistor’s resistive element.

However, when we apply a voltage difference across the terminals of resistors, it will start to resist the flow of current.

Now, moving charges such as electrons get attracted towards the positive terminal and move away from the negative terminal. The charges try to balance out the voltage difference by flowing through the resistive element.

This movement of charge carriers through the resistive element creates a resistive current, which starts to flow across resistors. So if R denotes the resistor’s resistance, V1 and V2 denote the voltages applied at its two terminals respectively.

Then, I = V/R becomes the current that flows through resistors.

In short, resistors resist the flow of current when a voltage difference is applied across the resistive element and in return, produces a resistive current.

## What are resistors made out of?

Resistors come in a variety of resistances, typically measured in Ohms (Ω). Resistors resist the flow of electric current. The resistivity of resistors changes depending on the materials that Resistors Resistors are made out of.

They can be made from the following different types of materials:

### Carbon Composition

Carbon composition resistors use carbon particles as their resistive element. Carbon resistors are cheap resistances, have a tolerance of 5-10%, and have low wattage ratings.

Carbon Composition resistors use carbon particles as their resistive element. Carbon resistors are cheap resistances, have a tolerance of 5-10%, and have low wattage ratings.

### Metal Film Resistors

Metal resistors resist the flow of current by the use of thin metal film deposited on ceramic, plastic, or even glass substrates. Metal resistors have very small resistances and resist the flow of current with high accuracy.

Metal resistors resist the flow of current by the use of thin metal film deposited on ceramic, plastic, or even glass substrates. Metal resistors have very small resistances and resist the flow of current with high accuracy.

### Wire-wound resistors

Wire Resistors are made out of resistive wire, usually made from Nichrome or Chromel alloys. Wire-wound resistors come in various shapes and sizes depending on their wattage ratings.

Wattage resistors resist the flow of current with high resistances. They can resist higher voltages than other resistors. Wire-wound resistors are available in various wattage ratings.

### Metal oxide resistors

These resist the flow of current by the use of resistive elements made out of metal oxides like manganese dioxide. Metal oxide resistors come in low resistances and resist voltages, which is not suitable for most electronic circuits.

## What are the roles of resistors in circuits

Although we have mentioned the primary function of resistors, it is important to know that they play different roles in different circuits. Let’s look at some of the key roles that resistors play in circuits.

-Used as potential dividers: Resistors are used in potential dividers to resist the change in voltage within a circuit.

-Used as load resistors: Resistors are also used to resist the flow of current instead of providing a source of energy. They mainly act as resistive loads. This is usually the case when resistors are connected in series.

-Used for limiting currents: Resistors are used to limit the maximum current flowing through a circuit to a resistive load.

-Used for biasing: Resistors are used in the circuits where resistors need to be biased concerning zero or ground potential.

-Used as voltage dividers: Resistors are generally connected in resistive voltage dividers for obtaining different reference voltages, which is very important in many applications.

-Used as overload resistors: Resistors are used as resistive loads to protect other components such as transistors and diodes from voltage surges.

-As current limiting resistors: Resistors are used to limit the maximum current flowing through a circuit to a resistive load.

-Impedance matching: resistors are used to match the impedance of a circuit to resistive loads such as resistive circuits.

-Used for decoupling: resistors are also used to avoid unwanted stable states in digital circuits where resistors are connected from inputs to ground through bypass capacitors.

– As circuit elements: resistors that have a particular value of resistivity are mainly used as resistive circuit elements in different electronic circuits. Resistors resist the flow of current with high resistances. They can resist higher voltages than other resistors.

– Used for filtering: Resistors are used in filters, where resistive element needs to filter out unwanted frequencies from signals while passing through a circuit.

## Types of Resistors

Now, let’s have a look at the different types of resistors. You will then be in a position to know which type to get for your need.

### Fixed value resistors

Fixed resistors resist the flow of current with a fixed resistive value. They are available in various resistances depending on their power ratings. Fixed resistors are available in wattage ratings ranging from 1/8-W to 250-Watts.

### Variable resistors

These resistors can be adjusted according to the needs of an application. Variable resistors are available in different resistances depending on their resistance value. They resist the flow of current through them with variable resistive values.

### Potentiometers

Potentiometers resist the flow of current through them with variable resistive values. Potentiometers are adjustable resistors that can be adjusted to get the required voltage or resistive values. They are used to adjust the output levels of audio circuits.

### Rheostats

Rheostats resist the flow of current through them with variable resistive values, just like potentiometers. The difference is that rheostats offer higher resistances than potentiometers and cannot be adjusted for resistance below one ohm.

### Resistor networks

Resistor networks resist the flow of current through resistive paths. They resist the flow of currents with resistive values and can be used to reduce total circuit resistance in designs such as voltage dividing networks, potential dividers, and many other circuits.

### Light-emitting diodes

As the name suggests these resistors have a light-emitting diode connected in series to resist the flow of current through them. They resist the flow of current with variable resistive values. LEDs are used mainly as status indicators in electronic circuits, which indicate ON/OFF conditions, etc.

### Varistors

These resistors resist high voltages or transients applied across it and keep on resisting the flow of current through it. Varistors resist currents with variable resistive values. They resist high voltages or transients applied across them and keep conducting the same current.

They remain in their conductive state even when subjected to high voltages and do not allow the voltage to rise above a certain limit within which resistors resist the flow of current.

### Zener diode resistors

When a Zener diode gets forward biased, it conducts through it with significant resistances. When a reverse voltage is applied across the Zener diode, its resistance decreases and allows the voltage to rise above a particular limit within which resistive circuits cannot resist the flow of current.

### Specialize resistors

Some resistors are designed to resist currents with variable resistive values. They resist voltage or transient current spikes. These resistors are available with either positive temperature coefficient (PTC) or negative temperature coefficient (NTC).

### Through-hole resistors

These resistors resist the flow of current through them with resistive values. They are mounted on printed circuit boards through insertion in holes punched out on the printed circuit board.

### Surface-mount resistors

They resist the flow of current with resistive values and are mounted on printed circuits simply by having their leads bent to get soldered at the desired spot on the printed circuit board.

### Chip resistor

These resistors resist the flow of current with resistive values and are made up of an oblong resistor-like chip enclosed in a ceramic material with leads on either side. These resistors resist the flow of current by having their leads bent to get soldered at the desired spot on the printed circuit board.

### Chassis mount resistors

They resist the flow of current with resistive values and resist voltage or transient current spikes. These resistors resist currents by having their leads bent to get soldered at the desired spot on the printed circuit board.

## Specifications and Parameters for Resistors

Before you buy resistors, it is vital to consider various resistor parameters and specifications. They determine the performance, reliability, and functionality of resistors. These parameters and specs include:

-Resistance value

-Power rating

-Tolerance

-Temperature coefficient

-Maximum voltage rating

-Stray inductance

-Surge handling

Resistance value:

The resistive values of resistors are indicated by a three-digit number. For resistors with resistive values between 0.1 and 100 ohms, the resistance value is indicated by three non-significant zeros followed by the first significant figure.

For resistors with resistive values between 100 and 1000 ohms, the resistance value is indicated by two non-significant zeros followed by the first significant figure. In both cases, the unit of resistivity is Ohm.

Power rating:

The resistors have a power dissipation rating in watts which tells about how much power they resist. Power dissipation is the product of voltage and current through resistors in a resistive circuit. In most cases, resistors have a power rating of 1/4 watt.

Tolerance:

The resistances with standard resistances have specified tolerance limits that are indicated by a single letter code or two-digit number preceded by a letter. For resistors with resistive values between 1 and 100 ohms, the tolerance value is indicated by single-letter code ‘E’ or by two-digit numbers preceded by ‘R’.

Temperature coefficient:

The resistivity of resistors varies with temperature because carbon composition resistors have positive temperature coefficients, whereas metal film resistors have negative temperature coefficients. With resistive values between 1 and 100 ohms, the resistor has a resistance value that varies with temperature by more than 10% of the resistive value.

Maximum voltage rating:

The resistors have a maximum voltage rating which tells about the highest safe operating voltage that resistors resist. In most cases, resistors have a maximum voltage rating of 200 Volts.

Stray inductance:

The resistors resist the flow of electric current through them with resistive values. They also cause voltage spikes that are transient because of stray inductance. Resistors resist voltage spikes by having their leads bent to get soldered at the desired spot on the printed circuit board.

Surge handling:

Resistors resist the flow of current through them with resistive values. They resist voltage spikes that are transient because of stray inductance. Resistors resist voltage spikes by having their leads bent to get soldered at the desired spot on the printed circuit board.

## Choosing Resistor Supplier

Regardless of the type or specifications of the resistors, it is always important to buy from a reliable source. By this, we refer to the best resistor manufacturers and suppliers. The resistors form a reputable resistor supplier provide you with the highest value for money. They resist voltage spikes, resist current, and resist high temperatures.

Check out the experience of the supplier.

The resistors you are planning to buy should resist voltage spikes, resist current, and resist high temperatures. For this reason, check out the experience of the resistor supplier.

Experience ensures that resistor manufacturers have manufactured resistors, which resist voltage spikes, resist current, and resist high temperatures for years together.