Question

The simplest type of vacuum tube is called a (an) _____.

Answer 1

Before the 1947 invention of the transistor the electron tube (also known as a 'Vacuum tube', or a 'Valve' ) was the basis of virtually all electronic devices. The simplest kind of electron tube is the diode, which was invented in 1904 by John A. Fleming. In Greek, “di” means “two,” and it was called a diode since it only had two electrodes inside—the negative electrode or “cathode” and the positive electrode or “anode.” Fleming’s diodes were modified light bulbs, so like light bulbs they consisted of a glass bulb with a filament inside. The filament acted as the cathode, emitting large numbers of electrons, while the anode consisted of a small metal plate mounted near the filament and connected to the outside of the tube by a thin wire.