Electronic Components

Electronic components are the individual parts from which circuits are built. They are broadly divided into passive and active types. Passive components, such as resistors, capacitors and inductors, cannot introduce energy or amplify a signal; they store, dissipate or shape current and voltage. Active components, mostly semiconductor devices such as diodes, transistors and integrated circuits, can control the flow of current and amplify or switch signals, drawing on a power supply to do so.

Semiconductor devices are central to modern electronics. A diode allows current to pass in one direction and blocks it in the other, which makes it useful for rectifying alternating current and for protection. A transistor can act as a switch or as an amplifier; the two main families are bipolar junction transistors and field-effect transistors such as the MOSFET. By combining many transistors on a single chip, manufacturers produce integrated circuits, including operational amplifiers used to amplify and process analogue signals.

Beyond these basic building blocks, a wide range of specialised components serves particular purposes. Optical sensors and photodetectors respond to light, laser diodes generate it, and devices such as triacs control mains power. Transient voltage suppressors protect circuits against damaging spikes, and transformers transfer energy between circuits while changing voltage. Understanding what each component does, and how passive and active parts work together, is the foundation of reading and designing circuits.

Frequently asked questions

What is the difference between passive and active components?

Passive components such as resistors and capacitors cannot amplify a signal or add energy; they store or dissipate it. Active components such as transistors control current and can amplify or switch, drawing on a power supply.

What does a diode do?

A diode conducts current in one direction and blocks it in the other, which makes it useful for converting alternating current to direct current and for protecting circuits.

What is an integrated circuit?

An integrated circuit is a chip containing many components, often thousands or millions of transistors, fabricated together on one piece of semiconductor to perform a complete function.