Electrical Engineering Principles

What is resistor?

A resistor is an electrical component 

• limits or regulates the flow of electrical current in an electronic circuit.   

• Resistors in a circuit is to control the flow of current to other components.  

A Resistor works on the principle of Ohm's law and the law states that the voltage across the terminals of a resistor is directly proportional to the current flowing through it. 

The unit of resistance is Ohm.  Symbol is omega or  Ω.

Resistor material  

• carbon-composition resistors 

• carbon-film resistors 

• metal-film resistors

The most common type of resistor consists of a small ceramic (clay) tube covered partially by a conducting carbon film. 

Non Linear Resistors

This type of resistor different where the current flowing through it does not change according to Ohm’s Law but, changes with change in temperature or applied voltage. When the flowing current through a resistor changes with change in body temperature, then these kinds of resistors are called Thermister. If the flowing current through a resistor change with the applied voltages, then it is called a Varistors or VDR (Voltage Dependent Resistors).

Following are the additional types of Non Linear Resistors.

• Thermisters

• Varisters (VDR)

• Photo Resistor or Photo Conductive Cell or LDR

Linear Resistors

Those resistors, which values change with the applied voltage and temperature, are called linear resistors. In other words, a resistor, which current value is directly proportional to the applied voltage is known as linear resistors. Generally, there are two types of resistors which have linear properties.

• Fixed Resistors

• Variable Resistors

Fixed Resistors

As the name tells everything, fixed resistor is a resistor which has a specific value and we can’t change the value of fixed resistors.

Types of Fixed resistors.

• Carbon Composition Resistors

• Wire Wound Resistors

• Thin Film Resistors

• Thick Film Resistors

Variable Resistors

As the name indicates, those resistors which values can be changed through a dial, knob, and screw or manually by a proper method. In these types of resistors, there is a sliding arm, which is connected to the shaft and the value of resistance can be changed by rotating the arm.  Following are the types of Variable Resistors

• Potentiometers

• Rheostats

• Trimmers