Resistor Basics and Definition

A resistor is a passive electrical component and has two-terminals. It implements electrical resistance as a circuit element. Fixed resistors have resistances that only change slightly with temperature, time or operating voltage. Variable resistors can be used to adjust circuit elements (such as a volume control or a lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity.

Resistors are common elements of electrical networks and electronic circuits and are ubiquitous in electronic equipment. Practical resistors as discrete components can be composed of various compounds and forms. Resistors are also implemented within integrated circuits.

Applications of Resistor

• reduce current flow
• adjust signal levels
• to divide voltages
• bias active elements
• terminate transmission

Resistors Symbol

The international IEC symbol is a rectangular shape. In the USA the ANSI standard is very common, thisis a zigzag line Resistor Colour Codes

Resistor Colour Codes

• Each colour band (strip, ring etc.) is associated with a number as represented below:
• Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Purple=7, Grey=8, White=9
• Find the tolerance colour band, typically gold (5%) and sometimes silver (10%).
• Starting from the other end, identify the first colour band and write down the number associated with that colour as in the chart above.
• Identify the next colour band and write down the number associated with that colour.
• Identify the next colour band and write down that number of zeros. The third band or ‘”multiplier” band indicates the number of zeros.