Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Semiconductors and Electronic Devices

Question:

In a vacuum tube, the electrons are supplied by a heated cathode and the controlled flow of these electrons in vacuum is obtained by varying the voltage between its different electrodes. What is the purpose of vacuum ?

Options:

to create a low pressure inside the tube

to create a high pressure inside the tube

to avoid collision between the air molecules and the electrons

to avoid the electric discharge

Correct Answer:

to avoid collision between the air molecules and the electrons

Explanation:

Vacuum is required in the inter-electrode space; otherwise the moving electrons may lose their energy on collision with the air molecules in their path