electronics, Branch of physics that deals with the emission, behaviour, and effects of electrons and with electronic devices. The beginnings of electronics can be traced to experiments with electricity. In the 1880s Thomas Alva Edison and others observed the flow of current between elements in an evacuated glass tube. A two-electrode vacuum tube constructed by John A. Fleming (1849β1945) produced a useful output current. The Audion, invented by Lee De Forest (1907), was followed by further improvements. The invention of the transistor at Bell Labs (1947) initiated a progressive miniaturization of electronic components that by the mid-1980s had resulted in high-density microprocessors, which in turn led to tremendous advances in computer technology and computer-based automated systems. See also semiconductor.