Question

How is the controlled flow of electrons in a vacuum tube obtained?

पर्याय

• By changing the number of air molecules in their path

• By replacing the evacuated space with a solid

• By attaching a metal point contact to galena

• By varying the voltage between the different electrodes

Answer 1

Varying the voltage between the electrodes controls electron flow in a vacuum tube. The electrons themselves are supplied by the heated cathode.