Types Of Resistors – Applications, Conclusion And FAQs

Author: Harry

May. 13, 2024

Electronic Components & Supplies

Types Of Resistors – Applications, Conclusion And FAQs

In your daily life, you use many electronic appliances. Maximum appliances used at home consist of an electric component known as a resistor. These resistors are mostly used in heaters, light bulbs, microwaves, electric stoves, toasters, and other heating appliances. In an electronic circuit, the flow of the current or limits of current is done by a resistor. To provide a particular voltage range for an active device, resistors are used as transistors.

Types of Resistors

Resistors are classified into two types. These types of resistors are further divided into subcategories. The types of resistors are as follows:

Linear Resistor

The current in a linear resistor will be directly proportional to the voltage applied to it. The resultant graph of the linear resistor will be between the current (I) and voltage (V), resulting in a straight I-V curve.

Linear resistors are further divided into two types:

Fixed Resistors

Fixed resistors have specific values, which cannot be changed. These fixed resistors are used in appliances that never need to change their resistance value.

Variable Resistors

Variable resistors have values that can be varied using a dial, screw, button, or knob. These variable resistors are used for appliances like radios with knobs, light dimmers, and television.

Non-Linear Resistor

The current in a non-linear resistor is indirectly proportional to the voltage applied. The current changes with variations in temperature or voltage. Non-linear resistors do not follow Ohm's law. Their I-V graph is non-linear.

Non-linear resistors are further divided into three types:

Thermistors

Thermistors are a type of variable resistor sensitive to temperature. The resistance value of thermistor resistors is inversely proportional to temperature.

Varistors

Non-linear varistor resistors are made of semiconductors. The current through the varistor depends non-linearly on the voltage applied. The most commonly used varistor is the MOV (metal oxide varistor).

Photo Resistors

Photo resistors, also known as LDR (light-dependent resistors), have resistance that decreases with an increase in light intensity. They are also known as photoconductive cells or light-controlled variable resistors.

Types of Resistors: Fixed and Variable

Fixed and variable resistors are types of linear resistors. These can be further classified into sub-categories.

There are seven types of resistors, including the fixed resistor, which are as follows:

Wire Wound Resistor

Wire wound resistors are made by wrapping metal wire around a metal core, which restricts the flow of electric current.

Foil Resistor

Foil resistors are highly precise and generate little noise. They have a low Temperature Coefficient of Resistance (TCR).

Carbon Composition Resistor

These resistors limit the flow of electric current to a set level using a cylindrical resistive element made of a ceramic and carbon powder mixture.

Carbon Film Resistor

Carbon film resistors are made by applying a carbon film to a ceramic substrate. The ceramic serves as an insulator, while the carbon film acts as the resistive element.

Metal Film Resistor

Metal film resistors use metal film to limit current. They have a low TCR and are made from materials like chromium, nickel, tin, and antimony.

Metal Glaze Resistor

The metal glaze resistor is made by combining glass powder with metal particles to limit electric current. They have a low TCR.

Metal Oxide Film Resistor

Metal oxide film resistors use metal oxide film as the resistive element and are constructed similarly to metal film resistors.

There are seven types of variable resistors, which include:

Potentiometer

Potentiometers have three terminals: two fixed and one movable. Adjusting the resistance of the potentiometer alters the current flow.

Humistor

Humistors are sensitive to humidity and are also known as resistive humidity sensors.

Rheostat

Rheostats are similar to potentiometers but use only two terminals. The length of the resistive track determines the resistance.

Thermistor

Thermistor resistance varies with temperature. PTC (Positive Temperature Coefficient) thermistors increase resistance with temperature, while NTC (Negative Temperature Coefficient) thermistors decrease resistance with temperature.

Magneto Resistor

Magneto resistors change resistance when exposed to a magnetic field, decreasing resistance as the magnetic field's strength increases.

Photoresistor

Photoresistors change resistance when light energy is applied. Their resistance falls as the light intensity increases.

Force Sensitive Resistor

Force-sensitive resistors change resistance when force is applied, making them useful for sensors and pressure-sensitive applications.

Things to Consider When Using Various types of fixed resistors

Power dissipation and temperature coefficients are the two factors to be mindful of when using a resistor:

  • Power Dissipation: Always select a resistor with a power rating higher than the current being passed through it, ideally twice as high.
  • Temperature Coefficients: Resistors must be used within specified temperature ranges to avoid significant changes in resistance. The temperature coefficient of a resistor can be either positive (PTC) or negative (NTC).

Color Code of Resistors

The resistance value of a resistor is often not displayed directly but can be calculated using a color coding system. Plated-through-hole (PTH) resistors use colored bands for identification, while surface-mount device (SMD) resistors have their own value markings.

Tolerance of Resistors

The deviation of a resistor's value from its nominal value is known as tolerance, expressed with the ±% symbol. Tolerance helps in identifying the resistor and provides a more accurate resistance reading.

  • Color Tolerance:
  • Brown: ±1%
  • Red: ±2%
  • Gold: ±5%
  • Silver: ±10%

Applications of Resistor

Wire wound resistors are used in shunts with ammeters for accurate current measurement. Photo resistors find applications in photography equipment, burglar alarms, and flame detectors. Resistors are crucial in devices like voltmeters, oscillators, digital multimeters, and amplifiers. They are also essential in telecommunication equipment and various electronic circuits.

Conclusion

Resistors are essential in electronic appliances and circuits. Practical experience with resistors aids in understanding their usage and operation in circuits. Different types of resistors have varied behaviors, and choosing the right type for a circuit is crucial. Refer to the resistor color coding table to determine the appropriate resistor for specific applications.

For more details on how many types of resistor, visit here.

Frequently Asked Questions

1. What are the different types of resistors?

There are many types of resistors. The main classification of resistors includes linear and nonlinear types. Linear resistors are further divided into fixed and variable resistors, while nonlinear resistors include thermistors, photoresistors, varistors, and surface mount resistors.

2. Which type of resistor is used in chargers?

Flameproof wire wound resistors are used in chargers as they limit the current flow using a metal wire wrapped around a metal core, preventing high voltages.

3. What type of resistor is used in a bulb?

The type of resistor used in a bulb is tungsten. The filament's resistance increases with voltage, causing the bulb to glow as the current and temperature rise.

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