Electronic circuits are integral parts of almost all the technological advances being made in our lives today. Television, Radio, Phones and Computers immediately come to mind, but electronics are also used in automobiles, kitchen appliances, medical equipment and industrial controls. At the heart of these devices are active components, or components of the circuit that electronically control electron flow, like semiconductors, Vacuum tubes etc. However, these devices can not function without much simpler, passive components that predate semiconductors by many decades. Unlike active components, passive components, such as resistors, capacitors and inductors, can't control the electron flow with electronic signals inputs.

Passive electronic components are components that consumes energy. It does not produce energy, is incapable of power gain. Passive components simply absorb energy. A typical example of passive electronic components would be resistors and capacitors. For a closer look at these devices, let’s look below.

Resistors

A resistor is a passive two-terminal electrical component that introduce electrical resistance as a circuit. Resistors reduce current flow and at the same time, act to lower voltage levels within circuits. In electronic circuits resistors are used to limit current flow, to adjust signal levels, to provide bias to active elements, terminate transmission lines and many other uses. High-power resistors that can dissipate many watts of electrical power as heat may be used as part of motor speed controls, in power distribution systems, or as test loads for generators. Resistors may have fixed resistances that only change a little with temperature, time. Variable resistors can be used to adjust circuit elements (such as volume control or lamp dimmer), or as sensing devices for heat, light, humidity, force, or chemical activity. When two resistors are connected in series as then their total resistance equals the sum of individual resistance.

Resistance: It is the property of a material which opposes the flow of electric current through it. Conductors have low resistance while insulators have very high resistance. It is measured in Ohms.