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What Is a Cathode-Ray Tube (CRT)?

Diving into the world of technology, it is crucial to understand its roots. One such root lies in the Cathode-ray Tube (CRT), a discovery that revolutionized the way we perceive electronic devices.

What is a cathode-ray tube?

A cathode-ray tube is a vacuum tube containing one or more electron guns, the sources of electrons, that are accelerated and deflected onto a phosphorescent screen to create images. It plays a significant role in the history of television, contributing to the early designs of televisions and computer monitors.

The creation of the cathode-ray tube

The origins of the cathode-ray tube go back to 1897 when Sir J.J. Thomson, an English physicist, discovered electrons using a cathode-ray tube. This was a significant breakthrough in the field of physics, which led to the development of television and computer monitors.

Initially, cathode-ray tubes were simple, straight tubes with a single electrode at each end. But with time, they evolved into more complex devices. They started incorporating multiple electrodes, allowing the beam of electrons to be focused and deflected. This evolution made it possible to create moving images on a screen, forming the basis of the television industry.

How does a cathode-ray tube work?

Understanding the functioning of a cathode-ray tube requires a basic explanation of physics. Inside the tube, electrons are fired from an electron gun situated at the narrower end of the tube. These electrons travel through a vacuum inside the tube towards a fluorescent screen at the wider end.

The screen is coated with phosphor, which glows when struck by an electron beam. On their journey from the electron gun to the screen, the electrons pass through a set of magnetic coils that deflect them. This deflection allows the electrons to hit different parts of the screen, creating an image.


The cathode-ray tube, a significant technological invention, has paved the way for the evolution of television and computer monitors. While its usage has declined with the advent of more modern technologies like LCD and LED, the cathode-ray tube remains a crucial part of our technological history. 

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