What is a Resistor

A resistor resists the flow of electric current through an electrical component. A resistor has two terminals along which the electric current flows and it is designed so that the voltage of the current drops as the electricity passes in between the two terminals.  Thus, a resistor is mainly used to create and maintain a safe level of current in an electrical component. The resistance in a resistor is measured in ohms a SI unit used after ohm’s law.  The ohms law states that the electrical resistance is equal to the drop in the voltage between the two terminals of the resistor divided by the current that is being applied to the resistor. Thus higher the ohm value higher is the resistance to the current.

What Is A Resistor?

The physical component of the resistor determines the amount of resistance offered.  A carbon resistor consists of a resistive carbon packed in a ceramic cylinder. However, a carbon film resistor has a similar tube around which a conductive carbon film is wrapped on the outside. Metal film or metal oxide resistors are made in the same way but has metal instead of carbon. At very high power levels wirebound resistors are used in which metal wire is wrapped around the clay, plastic or fiberglass tubing. A resistor that can endure high heat is built using tantalum, a rare metal or materials such as cermet is used for applications that require high temperatures.

The resistors are protected by covering it with molded plastic or coat it with paint or enamel. The resistors are very small in size and hence nothing can be written on it. So, color coding is used to identify them. There are four colors in which the first three colors represent ohm value while the fourth one indicates its tolerance as to how much close by percentage is the resistance to its ohm value. This is very important because it decides the amount of current that flows into the device. The design of the resistor is imprecise and a current greater than the maximum value can change the resistor or even burn the unit.

Types Of Resistor:

There are two types of resistor; fixed or variable. As the name suggests a fixed resistor has a fixed or predetermined amount of resistance to current, whereas, a variable resistor is the one whose resistance can be varied to give different levels of resistance. The variable resistors are also called as potentiometers and are used in audio devices as volume controls. For high voltage devices a variable resistor is used called as rheostat, whereas varistors are resistors which change their resistance in response to high voltage. Thermistor raises or lowers the resistance based on the rise or fall of the temperature.  We have light resistance resistors also.                                    

The resistors are components of electric devices that resist the flow of current and hence control the voltage. It is measured in ohms. Resistors are found in almost all electrical applications and are of two types fixed which have fixed resistance and variable which can be changed based on the requirement.