Work of Sir J. J. Thomson Between 1894 and 1900 a series of experiments was carried out by Sir J. J. Thomson in the Cavendish Laboratory at Cambridge to determine the mass and charge of the electrons as well as the speed with which they travelled between the electrodes. He found that the electrons were all alike …
Energy conveyed by cathode rays One of Sir William Crookes’s tubes contained a small paddle wheel running on rails inside it and having mica vanes (Fig. 44.6). The two electrodes are arranged in such a way that cathode rays impinge only on vanes above the axis. On passing the discharge the paddle wheel rotates towards the anode. …
Cathode rays convey negative charge Professor Jean Perrin of the University of Paris designed a tube to demonstrate that cathode rays convey negative charge (Fig. 44.5). The anode of this tube is an aluminium tube open at both ends, inside which is an insulated metal cylinder, called a Faraday cylinder, having a small opening at one end. …
Cathode rays deflected by a magnetic field The path of cathode rays can be rendered visible by allowing them to impinge upon a screen coated with zinc sulphide and placed at a small angle to the line joining the electrodes of the discharge tube (Fig. 44.4). If a bar magnet is placed at right angles to the …
Nature of cathode rays During ·the last years of the nineteenth century experimental evidence gradually accumulated which demonstrated beyond doubt that cathode rays consist of streams of particles of negative electricity now known as electrons.
The Maltese cross tube. Cathode rays In 1859, Julius Plucker of Bonn University made a special tube, the anode of which was a Maltese cross made of aluminium (Fig. 44.3). This cast a sharp shadow on the end of the tube, suggesting that some kind of radiation was proceeding in straight lines from the cathode towards the anode. …
Crookes dark space During the last decade of the nineteenth century a number of investigators began to seek an explanation of the discharge phenomena. Interest became centred on what happened inside the Crookes dark space, and various tubes were made which were evacuated to such a pressure that the whole of the space between the electrodes was occupied …
Discharge tube phenomena In order to study the electric discharge in air at low pressure an extra high tension (e.h.t.) unit is required. This is used to apply a potential difference of 1000V or more between two electrodes at opposite ends of a glass tube 15 or more em long. The tube is connected to a vacuum …
Electrons in gases and vacuum It was known to the scientists of the eighteenth century that the succession of sparks from an electric machine changed to a quiet luminous discharge when the pressure of the surrounding air was reduced. One of the investigators of this phenomenon was a Fellow of the Royal Society named William Watson, who, in …