The Electric Guitar

The popularity of the electric guitar began with the big band era because amplified instruments became necessary to compete with the loud volumes of the large brass sections common to jazz orchestras of the thirties and forties. Initially, they consisted primarily of hollow "archtop" acoustic guitar bodies to which electromagnetic transducers had been attached.
Electric guitars were originally designed by an assortment of luthiers, electronics enthusiasts, and instrument manufacturers, in varying combinations. Some of the earliest electric guitars used tungsten pickups and were manufactured in the 1930s by Rickenbacker.
Operation
In contrast to the acoustic guitar and most other acoustic string instruments, the solid-body electric guitar does not rely as extensively on the acoustic properties of its construction to amplify the sound produced by the vibrating strings; as such, the electric guitar does not need to be naturally loud, and its body can be virtually any shape.
Since all the sound produced by the amplifier comes from string vibrations detected by the electric pickups, an electric guitar that produces minimal acoustic sound may have maximal sustain, since less of the energy from the string oscillations is radiated as sound energy. For this reason, electric versions of almost all other similar string instruments have also been produced.

clip on guitar tuner
clip on guitar tuner