Which of the following components can consist of three regions of semiconductor material?
Why A bipolar junction transistor is made from three doped semiconductor regions arranged as NPN or PNP: the emitter, the base, and the collector. Current flowing into the thin base region controls a much larger current between emitter and collector, which is how the device provides gain. A diode, by contrast, has only two regions and one junction.
Watch out A triode is a vacuum tube with three electrodes (cathode, grid, plate), not semiconductor regions, and a pentode is a five-element tube; an alternator is a rotating machine that generates AC.
Tri-ode and penta-ode are tubes counting electrodes; the transistor counts three doped regions: emitter, base, collector.