A loudspeaker, which is also called a speaker, is a device that is used to create the sound in radios, television sets, and electric musical instrument amplifier systems.
Loudspeakers use both electric and mechanical principles to convert an electrical signal from a radio, television set, or electric musical instrument into sound. For a loudspeaker to produce sound, the signal from the radio, television set, or electric musical instrument needs to be connected to an electronic amplifier.
Loudspeakers are usually built by using stiff paper cone, a coil of thin copper wire, and a circular magnet. The cone, copper wire, and magnet are usually mounted in a rectangle-shaped wood cabinet. The coil of copper wire moves back and forth when an electrical signal is passed through it. The coil of copper wire and the magnet cause the rigid paper cone to vibrate and reproduce sounds.
Some loudspeakers are designed for lower-pitched sounds, such as woofer loudspeakers or subwoofer loudspeakers. Other loudspeakers, which are called tweeters, are designed to reproduce high-pitched sounds (such as the sound of a whistle or a bird singing).
Loudspeakers for electric musical instruments are usually much stronger and heavier than loudspeakers for radios or television sets.Loud speakers main function is to convert electrical signals given to it into sound signals.
Alexander Graham Bell invented the first loudspeaker in 1876. Bell invented the loudspeaker because he needed a device that would amplify sound for the telephone. In 1878, Ernst Siemens from Germany invented an improved type of loudspeaker.
For More Information: Loudspeaker K-12 Projects and Experiments
Source: Wikipedia (All text is available under the terms of the Creative Commons Attribution-ShareAlike License)