Cathleen Shamieh

Electronics is more than just schematics and circuits. By using various components, such as resistors and capacitors, electronics allows you to bend electric current to your will to create an infinite variety of gizmos and gadgets. In exploring electronics, use this handy reference for working with Ohm’s, Joule’s, and Kirchhoff’s Laws; making important calculations; determining the values of resistors and capacitors according to the codes that appear on their casings; and using a 555 timer and other integrated circuits (ICs).

You need a closed path, or closed circuit, to get electric current to flow. If there's a break anywhere in the path, you have an open circuit, and the current stops flowing — and the metal atoms in the wire quickly settle down to a peaceful, electrically neutral existence. A closed circuit allows current to flow, but an open circuit leaves electrons stranded.

The figure shows the front and back of one type of mini-speaker. Speakers usually come with leads attached. The leads are twisted together to keep things neat and tidy. You attach the leads to components in your circuit so that electrical current passes from your circuit into the speaker. The speaker then converts the current into sound.

A capacitor is a pretty simple device. It consists of two electrical conductors (known as plates) that are separated by a special type of insulator (that is, a nonconductor) known as a dielectric (pronounced "die ih LECK trick").Leads are attached to each plate and a coating or other case is placed around the capacitor.

You may be familiar with LEDs if you have an LED flashlight or use LED bulbs in your home. An LED, or light-emitting diode, is a device made of a special material known as a semiconductor. A diode is the simplest type of semiconductor device (meaning, component). Diodes, LEDs, and other semiconductor devices have unique properties that make them useful.

In scientific terms, radio is the transmission of a certain kind of electromagnetic energy through the air. Electromagnetic energy is energy that is radiated (meaning emitted) by an object and travels in waves, similar to the way sound is transmitted. X-rays, microwaves, visible light, and ultraviolet light (think sunburn) are other types of electromagnetic energy.

A pushbutton switch is a type of tactile (meaning touch) switch, which is an on/off switch that is activated when pressure is applied to it (usually by a finger).The figure shows one type of pushbutton switch. Each of the eight switches is a normally open, momentary single-pole, single-throw (SPST) pushbutton switch.