Question

what is vacuum tube ​

Answer 1

Explanation:

A vacuum tube, also called a valve in British English, is an electronic device used in many older model radios, television sets, and amplifiers to control electric current flow. The cathode is heated, as in a light bulb, so it will emit electrons. This is called thermionic emission. ... Vacuum tubes must be hot to work.

Answer 2

Answer:

It is a device that controls electric current flow in a high vacuum between electrodes to which an electric potential difference has been applied.