Resistors are electrical components that are used in electrical circuits to manipulate current flow. They are individual components and are measured in ohms that range from less than 1 ohm to well over millions of ohms. The higher the value of the resistor, the more resistance it has against current flow. The component itself is too small to have a value written over it, thus there are colour codes printed on the resistor.
Resistors however can be classified into two groups, fixed resistors and variable resistors. The printing of colour codes does not apply to variable resistors which are also known as potentiometers. Variable resistors have three leads coming out of the component where two are used to connect to a circuit and one is movable to adjust the resistance. Variable resistors are commonly found in devices that require the resistance to be manipulated; for example brightness control on a mobile phone.
Fixed resistors on the other hand can also be classified into three categories; carbon composition type resistors, wire wound resistors and metallized resistors. The carbon composition type resistors are the most common type of resistors as they are cheap and durable. They usually have low values and are made of carbon-clay material for the resistive portion of the resistor and the leads to be connected to a circuit are made of tinned copper.
The wire wound resistors make use of a wire made of resistive material wounded around an insulating core which is then coated with an insulating material. Metallized resistors, on the other hand, are made by coating a glass or ceramic rod tube with high resistive metal.
Resistors play a crucial role in everyday electronic devices. We may not realize the importance of these tiny components, but if it was not for them, our electronic devices would have been burnt by the high voltage present in electricity mains in our homes.