Question

Before the discovery of the transistor in 1948, which devices were mainly used to obtain a controlled flow of electrons?

Options

• Liquid Crystal Display monitors

• Vacuum tubes, also called valves

• Galena crystals without a metal point contact

• Solid-state semiconductor junctions

Answer 1

Vacuum tubes, or valves, were the main devices used before the transistor was discovered in 1948. The transistor marked a transition away from those devices.