THE DISCOVERY OF THE ELECTRON (Reader At Work 2 - 42.Metin)
In the mid-1800's scientists wanted to know whether the atom was really indivisible. They also wanted to know why atoms of different elements had different properties. A major breakthrough came with the invention of the Crookes' tube. or cathode-ray tube. What is a cathode-ray tube and how does it work? Everybody knows that some substances conduct electric current; that is, they are conductors, while other substances do not. But with enough electrical power, a current can be driven through any substance - solid, liquid, or gas. In the cathode-ray tube, a high voltage electric current is driven through a vacuum. The tube contains two pieces of metal, called electrodes. Each electrode is attached by a wire to the source of an electric current. The source has two terminals, positive and negative. The electrode attached to the positive electric terminal is called the anode; the electrode attached to the negative terminal is called the cathode. Crookes showed that whe