Types of Resistors

Defining a resistor (also known as an electrical resistor) as a two-terminal passive electrical element that offers electrical resistance to the flow of current is straightforward. The resistance of a resistor is a measure of the resistance to the flow of electricity in the resistor. The greater the resistance of a resistor, the bigger the barrier it creates between the flow of current and the rest of the circuit. As the name implies, the fundamental function of a resistor in an electrical and electronic circuit is to “resist” the flow of electrons (i.e., electric current). That is why it is referred to as a “resistor.”

Availability of resistors in a variety of shapes and sizes

The structure of these resistors, as well as their power dissipation capacity and tolerance to certain parameters, differ (such as temperature and light). The following are examples of resistors:

Carbon Composition Resistor: A composition resistor (also known as a carbon resistor) is a type of resistor that is widely used in electronic devices. Low-cost and simple-to-assemble resistors are used in this application. Carbon resistors are primarily composed of a carbon clay composition that is enclosed in a plastic casing. The resistor’s lead is comprised of copper that has been tinned.

One of the most significant advantages of these resistors is that they are readily available, inexpensive, and extremely durable.

There is also a large range of values available for these resistors, ranging from as low as 1 ohm to as high as 22 Mega ohms. As a result, carbon composition resistors are frequently included in many of the top Arduino starting kits available on the market.

Thermistor: The resistance value of the device changes in response to changes in temperature. The majority of thermistors have a negative temperature coefficient, which indicates that their resistance decreases as the temperature rises.

Semiconductor materials are typically used in the construction of these devices. Thermistors are capable of producing resistances of several mega ohms or more.

Wire Coiled Resistor: A wire of manganin or constantan is wound around a cylinder of insulating material in a wire wound resistor. When it comes to manganin and constantan, the temperature coefficient of resistance is almost nil. As a result, the resistance variation of these resistors with temperature is low.

In order to protect the wire from further damage, it is covered with an insulating material such as baked enamel. This cover is made of an insulating, heat-resistant polymer that resists the effects of temperature variations in the surrounding environment.

It is simple to get variable sizes and ratings for wire wound resistors by varying the length and diameter of the wire used in their construction.

Metal Film and Carbon Film Resistor: Resistances made of pure carbon or metal are known as metal film and carbon film resistors, and they are created by depositing a thin film of a conductive substance such as pure carbon or metal on an insulating core.

When working with metal film resistors or carbon film resistors, obtaining the desired value of resistance is as simple as reducing the layer thickness or cutting helical grooves of appropriate pitch along their length. At both ends of the resistor, a metallic contact cap is used to ensure proper contact. The conductive film or helical grooves are in contact with the caps, which is a good thing. The end caps of the lead wire are soldered to the end caps.

Electric resistors made of carbon film have lower tolerances and smaller electrical resistance values than those produced by resistors made of metal film. The carbon film, on the other hand, has a modestly negative temperature coefficient of resistance, which makes it extremely helpful in some types of electrical circuits.

Variable Resistor: The term “variable resistor” refers to the fact that the resistance value of the device can be modified (similar to a potentiometer). There is a revolving shaft as well as a wiping contact on the device.

To put it simply, there is a resistive semi-circular bar or coil, and wiping the contact changes the effective length of the resistive element, resulting in a change in resistance. A rheostat is an example of a resistor of this type.

Varistor: Non-Linear Resistor or Varistor:  they are known for having the non-linear V-I characteristics curve, which makes them very useful. That is, its resistance is not uniform, and it does not follow Ohm’s rule in any way.

Light Dependent Resistor: When light shines on a Light Dependent Resistor (LDR), the resistance of the device will change in proportion to how much light is being reflected off of it. If the lamp is not lighted, the material used to make it, cadmium sulphide, contains a low concentration of electrons.

A laser beam strikes it, and electrons are expelled from the material, increasing the conductivity of the material. As a result, it has a low resistance when light shines on it and a high resistance when darkness falls on it.

Conclusion

Resistors are the most fundamental and widely utilised of all electronic components, to the point that they are practically taken for granted. However, they play a critical role in the operation of a circuit and should not be underestimated.

Resistors are available in a variety of sizes and shapes, ranging from very small surface mount chip resistors to huge wire-wound power resistors.