Cathleen Shamieh

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.

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.

Capacitors are extremely useful in electronics and, chances are, you've used them many times without realizing it. Here are some places where you may have met up with capacitors: Alarm clocks: Many alarm clocks keep charged capacitors on hand in case there's a power failure. When the power goes out, the capacitor discharges — sending current through the clock circuit to keep the circuit running.

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.

Diodes do a simple but important job: They allow current to flow in just one direction. A special kind of diode — a light-emitting diode, or LED — is often used for the purpose of, well, lighting up. You have to be careful to orient the LED the correct way, or current won't flow at all.Another kind of diode performs the important task of preventing current from flowing the wrong way in your circuit.

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.

Pot is the shortened name for a potentiometer. A potentiometer (pronounced "poe-ten-shee-AH-meh-ter") is a variable resistor. The pot enables you to vary the blink rate of the LED without changing any components in your circuit.Pots come in various shapes, sizes, and values, but they all have the following things in common: They have three terminals (or connection points).