He used a cathode ray tube to measure the charge/mass ratio of the cathode ray particles that we now know are electrons. 1897 English experimental physicist John Joseph Thomson discovered the electron, the first elementary particle, at Cambridge Universitys Cavendish Laboratory in 1897. Thomson measure in 1897?ġ897-John Joseph Thomson. Using this information Thomson determined the mass to charge ratio of an electron.

Then Thomson measured how much various strengths of magnetic fields bent the particles. Thomson was able to deflect the cathode ray towards a positively charged plate deduce that the particles in the beam were negatively charged. Thomson performed experiments to show that atoms consisted of sub atomic particles that had positive and negative charges. Thomsons experiment to determine the charge-to-mass ratio of electrons. In addition, he also studied positively charged particles in neon gas. He demonstrated that cathode rays were negatively charged. Thomson discovered the electron by experimenting with a Crookes, or cathode ray, tube. What quantity does Thomson measure in his cathode ray tube experiments?Ĭharge-to-mass ratio What experiment did J.J. Accordingly, he called his particles electrons.

Thomsons discovery established the particulate nature of electricity. With both magnetic and electric deflections observed, it was clear that cathode rays were negatively charged particles. In his classic experiment, Thomson measured the mass-to-charge ratio of the cathode rays by measuring how much they were deflected by a magnetic field and comparing this with the electric deflection.

Cathode ray experiment that j. thomson