Current flows through resistors when they resist the flow of current. This is a passive component, since it does nothing actively. This component sounds useless and boring, but it has a lot of value. Having a basic understanding of it – and How Does a Resistor Work in Circuits – will give you the ability to control them.
What Is a Resistor?
Electronic components such as resistors provide current flow resistance by providing a pair of terminals. Resistance is something that impedes the flow of electrons between two terminals of a power source. Current is electrons flowing between two terminals.
When a resistor is placed between two terminals, the current flowing between them is reduced (controlled). Resistors may be visualized as speed breakers for current flow.
In many cases, resistors can be thought of as fixed valves or constrictors that are fitted in between pipes. In the same way that water flows through pipes, current can be considered a flow of water, and resistors can be compared to fixed valves. The flow of water is reduced if the constriction is very narrow. In a similar manner, a high resistor’s resistance reduces the flow of current. A resistor can be made out of any material, except superconductors. It is considered a conductor if a material has a very low resistance. As an insulator, it is otherwise classified.
What Does a Resistor do?
Resistors limit and regulate current flow in electrical and electronic circuits, divide voltages, adjust signal levels, and bias active elements. Light-emitting diodes (LED) are typically regulated using many resistors connected in series. We will discuss other examples in the following paragraphs.
Create voltage drops to provide proper voltage
An electrical circuit requires a specific voltage for each element, such as a light or a switch. As a result, resistors are used to create voltage drops across elements to provide proper voltage.
Voltage spike protection
Snubbers suppress rapid voltage rises across thyristors using a series combination of a resistor and capacitor. As a result, the thyristor is protected from high voltage by a snubber circuit. Voltage spikes can also be prevented by using resistors. If a resistor is not used to control the flow of electrical current through LEDs, they will become damaged due to their sensitivity to high electrical currents.
How Does a Resistor Work?
The current can be reduced by a specified amount when a resistor is connected to a circuit. In most cases, resistors look the same from the outside. A ceramic rod surrounded by copper wire can be seen once cracked open. There is a direct correlation between resistance and copper turns. Since electrons have a harder time passing through thin copper, the resistance increases. In some conductor materials, electrons flow more easily than in insulators, as we have discovered.
A resistor’s resistance was related to the material used to make it, and George Ohm studied this relationship. With increasing length, a material’s resistance (R) increases. In other words, thicker and longer wires have a higher resistance. In contrast, resistance decreases with increasing wire thickness. This relationship can be explained by the following equation by Georg Ohm:
Types of Resistors
Different types and sizes of resistors are available. Through-hole and surface mount are the two most common types. Depending on the application, there may be static resistors, standard resistors, special resistors, or variable resistors in a pack.
There are two basic types of resistors as follows:
- Linear resistor
- Non-linear resistor
Linear resistors
A linear resistor will change its value according to the temperature and voltage applied. Generally speaking, linear resistors fall into two categories:
Fixed resistors: The resistor values cannot be changed since they have a specific value. A fixed resistor can be classified into the following types:
- Carbon composition resistors
- Wire wound resistors
- Thin film resistors
- Thick film resistors
Variable resistors: With the help of a dial, knob, and screw, these resistors can be adjusted to different values. Volume and tone are controlled by these resistors in radio receivers. Variable resistors can be divided into the following types:
- Potentiometers
- Rheostats
- Trimmers
Non-linear resistors
Ohm’s law does not apply to resistors, as their value changes with temperature and voltage. Non-linear resistors can be classified as follows:
- Thermistors
- Varisters
- Photo resistors
Types of Resistor Material
A variety of resistor materials are available, each with its own advantages and disadvantages, and each with its own uses, as follows:
Carbon film resistors: Applied resistance is increased by spirally cutting an insulating cylindrical core and wrapping a pure carbon film around it. The accuracy of this material is greater than that of carbon composite. The use of special carbon film resistors is needed for applications that require higher pulse stability.
Metal film resistors: Tantalum nitride is used to make metal film resistors, but nichrome is more commonly used. The resistive material consists of ceramics and metals. Carbon films are less stable, have a lower temperature coefficient, and are less tolerable than polymer films. Temperature coefficients range between 50 and 100 ppm/K with tolerances between 0.5% and 2%. In terms of high frequency properties, it’s better than wire-wound, but it has less stability than wire-wound.
Wire wound resistors: A wire wound resistor has a spiral core that is non conductive and used to wind resistance wire around it. Nickel-chromium resistance wire is made from ceramic or fiberglass with a vitreous enamel coating and a ceramic or fiberglass core. As the spiral winding has capacitive and inductive effects, it is not suitable for applications above 50kHz. For applications requiring high precision or power, it is best suited.
Precision resistors: A ceramic substrate is cemented over a thin bulk metal foil in precision resistors. In applications requiring high precision, it offers the highest accuracy and stability, as well as very low coefficients of resistance at low temperatures.
Metal oxide film resistors: Resistors made from metal oxide films. Metal oxides, such as tin oxide, are commonly used as resistive materials. Since it operates at a higher temperature, it is more reliable and stable in applications requiring higher endurance.
Carbon composite resistors: Resistors made from carbon composites are pressed in a cylindrical shape and baked with fine carbon particles and non-conductive ceramics. Depending on the body’s dimensions and the ratio between the ceramic and carbon materials, the resistance value will vary. The resistance decreases as the amount of carbon is increased. A maximum tolerance of around 5% is observed with carbon composition resistors, which have remarkable reliability but poor accuracy.
Resistor color codes
By looking at the color bands on a resistor, you can figure out its resistance.
- Three bands of rainbow-colored material are found on most resistors, followed by a space, and then four bands colored brown, red, gold, or silver.
- To make the rainbow bands appear on the left side of the resistor, turn the resistor around.
- You can get the resistance by counting the first two bands of the rainbow. Consider a resistor with colored bands, such as this one, with brown, black, and red bands along with a golden band. As shown below, brown indicates 1 while black signifies 0, so resistance will start at 10. Lastly, you find a decimal multiplier: it tells you how many zeros to add to the first two numbers after they have been multiplied by ten. The red color means two, so ten times ten times ten equals 100, and we get 1000. The resistor we are using has a resistance of 1000 ohms.
- As you figure out the resistance value, this final band will tell you how accurate it will be. In the case of a gold band at the end of the chart, the resistance is within plus or minus 5%. It is likely that the resistance is between 950 and 1050 ohms, despite the official stated resistance being 1000 ohms.
- Five banded instruments have three resistance bands (instead of four), a decimal multiplier band, and a tolerance band. The tolerance value for five-band resistors is lower than the tolerance value for four-band resistors because they are necessarily more precise.
Faqs
Question 1: How do resistors resist current?
Answer: By adding a resistor, the circuit’s current is decreased. What causes this to happen? As an example, resistors are made out of less conductive materials than wires. Since electrons cannot move as fast in resistors as in wires, the resistor serves as a slowing device.
Question 2: Does a resistor reduce current?
Answer: The purpose of resistors is to limit current flow when there is an excess flow. Electrons and voltage are involved. Current is calculated by counting the number of electrons passing a given point at any given time, and voltage is the force pushing electrons around.
Question 3: How do resistors affect voltage?
Answer: Series circuits are made up of individual resistances, each contributing to the total resistance. The voltage drops in a series circuit are equal in magnitude to the sum of the voltages applied to each phase. In a series circuit, voltage drops across resistors are directly proportional to their sizes.
Final Verdict
There’s a lot to talk about and how does a resistor work in a real time application. But in this article, I will try to cover most of the important things which you need to know about the resistor, and its working principles. Still if you have any doubt or question, you can ask in the comment section. Our team is always to clear alo of your confusion in no time. Thank You.
