A proposal with low cost for cathode ray experiments

Abstract

This paper presents a proposal for the adaptation of one of the experiments on the nature of the cathod rays performed at the end of the 19th century, specifically the one presented in textbooks and scientific dissemination as "the Thomson experiment" for the calculation of charge /mass ratio of the electron. Our proposal uses materials at a lower cost than experiment kits available on the market and presents a detailed description of its construction and operation, and contributes in several respects as a solution to some of the reasons related to the low utilization of experiments in science classes: the high cost materials and equipment, the lack of laboratories and the lack of ability of teachers. The elaboration of the experimental apparatus is also accompanied by the mathematical development necessary for its use and the indication of the various physical phenomena that can be treated in parallel with its implementation. With the experimental adaptation, we were able to measure and calculate the magnetic field to which the electrons are subjected inside a cathode ray tube, the potential difference between cathode and anode in the tube (electron acceleration voltage), the magnetic deflection that the electrons undergo, and to a good approximation the speed of translation of the electrons and the charge/ mass ratio of these particles.

Keywords

• relação carga/massa do elétron
• raios catódicos
• j. j. thomson e a estrutura da matéria