What is Resistor?

A Resistor acts as a main electronic component in regulating or limiting the flow of an electric current in an electrical circuit. It is mainly used in electronic circuits because it acts as a current controller, it controls high and low voltage and it protects the components. The resistor mainly helps in regulating the flow of electricity in a circuit and it achieves the desired circuit behavior. Resistors are mainly used in electronic networks and electrical circuits to prevent from excess flow of current and to set the voltage levels in the circuit.

What is a Resistor?

The resistor can be defined as a passive electronic component with two terminals that produce electrical resistance to the flow of current in a circuit. It is measured in ohm(Ω). It can control limit or divide the electric current provided in the circuit, and its value can be determined by its resistance rating.

A Resistor contains four bands as shown in the below image:

• Band A in a resistor represents 1st digit.
• Band B in a resistor represents the 2nd digit.
• Band C in a resistor represents a Multiplexer.
• Band D in a resistor represents the % of Tolerance.

Different Types of Resistors

There are different types of resistors, which are mainly classified into Linear Resistors and Non-Linear Resistors.

Linear Resistors

In Linear Resistors, the value of resistance changes based on the applied temperature and voltage. These Linear Resistors are again classified into Fixed and Variable Resistors.

1. Fixed Resistors: In Fixed Resistors, the value of resistance is fixed and cannot be changed. These are mostly used in fixed circuits because the resistance value is fixed. Fixed Resistors are mainly used in electronic circuits where a stable or fixed resistance is required, For example: in voltage dividers or current limiters. Fixed Resistor follows Ohm’s law, which states, that voltage (V) is directly proportional to current (I) and resistance (R).

There are different types of Fixed Resistors:

• Carbon Film Resistor
• Wire Wound Resistor
• Metal Film Resistor

2. Variable Resistors: In Variable Resistors, the value is not specific and can be changed and can manually adjust the value of resistance by using the dial, knob of a screw. It is also known as potentiometer having two connecting wires instead of three. Variable Resistors are mainly used in applications where resistance needs to be variable, for example: in volume controls or sensor applications or radio receiver. There are the different types of Variable Resistors:

• Potentiometer
• Rheostat Resistor
• Trimmer Resistor

Non-Linear Resistors

In non-linear resistors, the value of resistance changes significantly with changes in voltage or current in an electrical circuit. This indicates the relationship between voltage and current is not proportional and it do not follow Ohm’s law. The resistor values change according to the temperature and voltage applied in the circuit. Non-linear resistors are mainly used in applications where resistance needs to be change based on the applied voltage or current. Non-linear resistors are mainly used in applications like voltage regulation or precise control.

There are different types of Non-Linear Resistors:

• Thermistors
• NTC (Negative Temperature Coefficient) Thermistor
• PTC (Positive Temperature Coefficient) Thermistor
• Varisters
• Photo Rresistors

Resistor Color Code

The value of resistance offered by a resistor is marked using a color code called Resistor Color Code. The resistors we use are very tiny and the printing of the value of resistance in the resistor is not feasible. Thus, to find the value of the resistor we use various color bands(mainly four color bands) that help to determine the value of the resistance. These color bands on the resistor are called the Resistor Color Codes.

1. Mnemonic of Resistor Color Code: Learning the Resistor Color Coding is very important and the mnemonic used to find the value of the resistor is:

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• The capital letters represent the first letters of the colors and their positions in the digit values. The representation of the color code as,
• Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, and White

Combination of Resistors

Resistors are used in various combinations. There are two methods of arranging the resistors in different combinations:

• Resistors in Series Combination
• Resistors in Parallel Combination

Equivalent Resistance: The equivalent resistance of combinations of resistors in series is equal to the sum of their individual resistances in the circuit.

1. Resistors in Series Combination

Two or more resistances are said to be connected in series when they are connected end to end and the same current flows through each of them in turn. In this case, the equivalent or the total resistance equals the sum of the number of individual resistances present in the series combination.

Mathematically, the equivalent resistance of any number of resistances (R1, R2, R3, R4, R5, ……..) connected in series is given as:

Req = R1 + R2 + R3 + R4 + R5 + ……..

2. Resistors in Parallel Combination

Two or more resistances are said to be connected in parallel connected when they are connected between two points and each has a different current direction. The current is branched out and recombined as the branches intersect at a common point in such circuits.

Mathematically, the equivalent resistance of any number of resistances (R1, R2, R3, R4, R5, ……..) connected in parallel is given as:

1/Req = 1/R1 + 1/R2 + 1/R3 + 1/R4 + 1/R5 + …..

Resistor Symbols

Working Principle of Resistor

Resistor is an passive electronic component which limits the flow of electric current in an electric circuit. It works on the principle of electrical resistance. It works mainly on resistance of an electrical circuit. Resistance has a property to opposes the flow of electric current. Resistance is measured in ohms(Ω).The more and the higher the resistance value of a resistor, the more it can restricts the flow of current passing through it.

By using Ohm’s Law: Resistor working principle can be explained using Ohm’s Law, which states that the current (I) flowing through a conductor is directly proportional to the voltage (V) across it and it is inversely proportional to its resistance (R). Mathematically, Ohm’s Law is represented as follows : V = I * R

Where,

• V stands for, the voltage across the resistor in volts (V).
• I stands for, the current passing through the resistor in amperes(A).
• R stands for, the resistance of the resistor in ohms(Ω).

Calculate the Resistance Value

• We need to consider the specific requirements of your circuit.
• We need to use Ohm’s law (R = V/I) to calculate it based on the required voltage (V) and current (I).
• We need to use R=V/I is the formula to calculate resistance value.

Applications of Resistor

• Resistors are mainly used in voltage division, as it helps to divide the voltage to its desired level in applications.
• Resistors are mainly used in limiting the current flow in any electrical component.
• Resistors are used in voltage regulators, sensors and temperature controller.
• Resistors are used in noise reduction process as it regulates the noise path.

Advantages of Resistors

The main advantages of using resistor in a electrical circuit are:

• Resistor helps in precise control of current and voltage in electrical circuit.
• Resistors can also be used as voltage dividers and current limiters in electrical circuit.
• Resistors are reliable, durable and they have a long operational life which helps in electrical circuits.

Disadvantages of Resistors

• Resistors are mainly designed for specific resistance values only, finding correct resistor sometimes may feel difficult.
• Resistors which are having high resistance will oppose large amount of electric current. so that the large amount of energy is wasted in the form of heat.

Conclusion

In conclusion, Resistors are main and fundamental components in an electrical components. They can help many electrical circuits to control current, voltage, and resistance with correct precision and reliability. Resistors has many applications in daily life. These are mainly used in electrical circuits. There are many different types of resistors. these each type of resistor is used in different types of circuits according their use. Resistors can help to control the flow of current, voltage and resistance.

FAQs on Resistors

Q.1: Can we use resistors to generate the heat intentionally?

Answer:

Yes, we can use resistors as heating elements. Because In household applications like electric stoves, toasters, and electric blankets are specially designed resistors, these are used to convert electrical energy into heat.

Q.2: Why Carbon composition resistors are less common these days?

Answer:

Carbon Composition resistors are made by mixing carbon and insulating materials. These resistors has a disadvantage in their resistance value that could drift over time, temperature, and humidity changes. Nowadays these Modern resistors like having metal film and metal oxide resistors, they offer better stability so they are commonly used.

Q.3:What is meant by “Chip Resistors” or “Surface Mount Resistors”?

Answer:

The small resistors are commonly known as “Chip Resistors” or “Surface Mount Resistors”. These “Chip Resistors” or “Surface Mount Resistors” are basically in rectangular or square shape .These are widely used in electronic devices and electronic circuits due to their compactness and their suitability for automated processes.