who is credited with first measuring the charge of the electron
Mass-to-charge ratio In the 19th century, the mass-to-charge ratios of some ions were measured by electrochemical methods. In 1897, the mass-to-charge ratio of the electron was first measured by J. J. Thomson.[6] By doing this, he showed that the electron was in fact a particle with a mass and a charge, and that its mass-to-charge ratio was much smaller than that of the hydrogen ion H+. In 1898, Wilhelm Wien separated ions (canal rays) according to their mass-to-charge ratio with an ion optical device with superimposed electric and magnetic fields (Wien filter). In 1901 Walter Kaufman measured the increase of electromagnetic mass of fast electrons (Kaufmann–Bucherer–Neumann experiments), or relativistic mass increase in modern terms. In 1913, Thomson measured the mass-to-charge ratio of ions with an instrument he called a parabola spectrograph.[7] Today, an instrument that measures the mass-to-charge ratio of charged particles is called a mass spectrometer.
Hans Christian Ørsted Hans Christian Ørsted (/ˈɜːrstɛd/;[2] Danish: [hans kʁæsdjan ˈɶɐ̯sdɛð]; often rendered Oersted in English; 14 August 1777 – 9 March 1851) was a Danish physicist and chemist who discovered that electric currents create magnetic fields, which was the first connection found between electricity and magnetism. He is still known today for Oersted's Law and the oersted (Oe), the cgs unit of magnetic H-field strength, is named after him. . He shaped post-Kantian philosophy and advances in science throughout the late 19th century.[3]