What Does a Cathode Ray Oscilloscope Do?

by Joost Nusselder | Updated on:  June 20, 2021
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The cathode ray oscilloscope or oscillograph is an electrical instrument used to convert electrical signals to visual signals. This instrument measures and analyzes the waveform and other electrical phenomena. It is also an X-Y plotter that plots the input signal versus another signal or time. The cathode ray oscilloscope is similar to a discharge tube; it lets you observe the electrical signals changes over time. This is used to analyze and calculate frequency, amplitude, distortion, and other time-varying quantities ranging from a low frequency to the radio frequency. It is also used in acoustic research and television production.

Main Components

Developed by a German physicist Ferdinand Braun the cathode ray oscilloscope consists of four main parts; which are the cathode ray tube, electron gun, deflecting system, and a fluorescent screen.

Working Principle

The electron gun generates a narrow beam of electrons, and the particle passes through the control grid. The control grid controls the intensity of the electron inside the vacuum tube. A dim spot is produced on the screen if the control grid has high negative potential, and low negative potential produces the bright spot in the control grid. So, the intensity of light is controlled by the negative potential of the control grid. Then the electrons are accelerated by the anodes which have high positive potential. It converges the electron beam at a point on the screen. After moving from the anode, this electron beam got deflected by the deflecting plates. The deflecting plate remains at zero potential, and the electron beam produces a spot on the screen center. The electron beam focuses on the upward if the voltage is applied to the vertical deflecting plate. The electron beam will deflect horizontally by applying a voltage to the horizontal deflecting plate.


The cathode ray oscilloscope is used in transmission as well as in the receiving unit of the television. It is also used in converting the electrical impulses corresponding to heartbeats into visual signals. For detecting enemy aircraft, it is also used inside the radar system and inside the laboratory for education purposes.


The cathode-ray oscilloscope works as a picture tube inside a television. The video signals sent from the television transmitter are applied towards the deflecting plates inside the cathode ray oscilloscope. Then the electron beam hits the screen, and the screen contains an array of tiny spots. Each spot is composed of three phosphor dots, representing the primary colors, the red, green, and blue. Phosphor dots glow as they get hit by the electron beam. If the beam of an electron is incident on more than one phosphor in a spot, then a secondary color is seen. A combination of three primary colors in proper proportion can produce a colored picture on the screen. When we view in front of the television, the phosphor-containing spot moves in a pattern similar to the movement of human eyes, at the time of reading a text. But the process takes place at such a rapid rate that our eyes see a constant image over the entire screen.

Education and Research

In a higher study, a cathode-ray oscilloscope is used for sessional. It is used to determine the waveforms, analyze its properties. Time-varying quantities are measured ranging from a low frequency to as large as radiofrequency. It can also measure the potential differences in voltmeter. Another advantage of this cathode-ray oscilloscope is that it can plot signals graphically and accurately measure short time intervals. The Lissajous figure can be plotted easily with the help of this instrument. For these reasons, an oscilloscope is used widely in higher study and research sectors.

Radar Technology

Radar is an electronic device that presents enemy aircraft data to the radar operator or the aircraft pilot. The radar system transmits pulses or continuous electromagnetic radiation waves. A small portion of that wave backscatter of targets and return to the radar system.
The receiver of the radar system contains a cathode ray oscilloscope, which converts the electromagnetic waves into a continuous electronic signal. The continuous electronic signal converted into an analog signal of varying voltage, which was later displayed to a display screen as an object.


Cathode ray oscilloscope or oscillograph is a revolutionized invention. It paved the way for making CRT television, which was the most wonderful invention of humankind. From a laboratory instrument to a vital part of the electronic world, it manifests as a human’s brilliance.

I'm Joost Nusselder, the founder of Tools Doctor, content marketer, and dad. I love trying out new equipment, and together with my team I've been creating in-depth blog articles since 2016 to help loyal readers with tools & crafting tips.

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