Transistor radio
A transistor radio is a small portable radio receiver that uses transistor-based circuitry. Following their development in 1954, made possible by the invention of the transistor in 1947, they became the most popular electronic communication device in history, with billions manufactured during the 1960s and 1970s. Their pocket size sparked a change in popular music listening habits, allowing people to listen to music anywhere they went. Beginning in the 1980s, however, cheap AM transistor radios were superseded by devices with higher audio quality such as portable CD players, personal audio players, boomboxes, and (eventually) smartphones, some of which contain radios themselves.
Invention of radio
It had been proposed in 1879 to German physicist Heinrich Rudolf Hertz that he try to prove Maxwell's theory of electromagnetism but he could not see any way to build an apparatus to experimentally test the theory. His observation, in the autumn of 1886, of discharging a Leyden jar into a large coil producing a spark in an adjacent coil gave him the idea of how to build a test apparatus. Between 1886 and 1888 Hertz conducted scientific experiments that validated Maxwell's theory. He designed a method of detecting spark-gap radio waves by observing that another unpowered spark-gap, acting as an antenna, would absorb the radio energy and convert it back into an electric spark. Hertz published his results in a series of papers between 1887 and 1890, and again in complete book form in 1893.