A transistor can amplify and switch electrical power and electronic signals. It is a semiconductor made of solid, non-moving parts that control the flow of electricity in circuits.
Transistors are largely used in electrical industry. Some of the first products that used them were transistor radios and hearing aids, which came into use in the early 1950s. Transistor radios work by amplifying signals. Radio stations take sounds recorded through a microphone and turn them into electrical signals. Those electrical signals travel through a circuit in the transistor radio, and the transistor then amplifies the signal, making it louder when it gets to the speaker. Transistors are made of semiconducting materials, such as silicone or germanium. The most common transistors are made in a protective case and generally have three electrical leads.
The transistor was invented by William Shockley, John Bardeen and Walter H. Brattain of the Bell Telephone Laboratories in 1948. The transistors’ better efficiency, size and cheap cost make them popular among consumers.