Definition: A cathode ray is a beam of electrons that travel from the negatively charged to positively charged end of a vacuum tube, across a voltage difference between the electrodes placed at each end. The electrode at the negative end is called a cathode; the electrode at the positive end is called an anode. Since electrons are repelled by the negative charge, the cathode is seen as the "source" of the cathode ray in the vacuum chamber.
With the 1650 invention of the vacuum pump, scientists were able to study the effects of different material in vacuums, and a more complete study of electricity soon followed. It was recorded as early as 1705 that in vacuums (or near vacuums) electrical discharges could travel a larger distance. Such phenomena became popular as novelties, and even reputable physicists such as Michael Faraday studied the effects of them.
In the late 1800s, physicist Phillip von Lenard studied the cathode rays intently and his work earned him the 1905 Nobel Prize in Physics.
The most popular commercial application of cathode ray technology is in the form of traditional television sets.
