What is Active Components and Passive Components?
All electronic circuits, however complicated, contain a few basic components (generally speaking, only five)—three passive and two active components. Though passive components by themselves are not capable of amplifying or processing an electrical signal but these components are as important in an electronic circuit, as active ones (such as transistors). Transistors cannot be used to amplify signals without the aid of passive components.
Active components or devices used in electronic circuits are numerous but all of these active components or devices can be broadly classified into two categories—tube type and semiconductor type devices.
Tube devices can be further divided into two categories—vacuum tubes (such as vacuum diode, vacuum triode, vacuum tetrode and vacuum pentode) and gas tubes (such as gas diode and thyratron). Semiconductor devices include junction diode, bipolar junction transistor (BJT), field-effect transistor (FET), unijunction transistor (UJT), silicon controlled rectifier (SCR), tunnel diode and zener diode. Tube devices came in existence first but now they have been replaced by the semiconductor devices owing to their inherent advantages.
Passive components include resistors, inductors and capacitors. These components are split into two categories; those which dissipate energy and those which store it. In the latter category is the inductor, which stores energy by virtue of a current passing through it, and the capacitor, which stores energy by virtue of a voltage existing across it. The third component, the resistor, is the only one of the three which dissipates electrical energy.