This is the official Video of Cathode Ray Tube by sir JJ Thomson.. A Cathode ray tube is the forerunner of the television tube. It is a glass tube from which most of the air has been evacuated. When the two metal plates are connected to a high-voltage source, the negatively charged plate, called the cathode, emits an invisible ray. The cathode ray is drawn to the positively charged plate, called the anode, where it passes through a hole and continues traveling to the other end of the tube. When the ray strikes the specially coated surface, the cathode ray produces a strong fluorescence, or bright light. When an electric field is applied across the cathode ray tube, the cathode ray is attracted by the plate bearing positive charges. Therefore, a cathode ray must consist of negatively charged particles. A moving charged body behaves like a tiny magnet, and it can interact with am external magnetic field. The electrons are deflected by the magnetic field. As expected, when the direction of the external magnet field is reversed, the beam of electrons is deflected in the opposite direction. In 1897, JJ Thomson, and English physicist, determined the charge-to-mass ratio of an electron. He adjusted the electric field so that the electrostatic deflection (0E) was the same as the magnetic deflection (0B), and was able to calculate the charge-to-mass ratio of an electron using the following equation: Where E is the applied electrical field, 0 is the angle of deflection, B is the applied magnetic field, and / is the distance traveled by the cathode rays. Thomson determined the charge-to-mass ratio of an electron to be -1.76 x 10 eight power coulombs per gram. hope i helped... ^^ Please Subscribe!.. and hit Like!