UNIVERSITY PHYSICS II CHAPTER 26 An Aperitif of Modern physics 826. 1 Some important discoveries at the end of the 20th century I. The discovery of the electron Spot of Filament To vacuum pump Measure the charge to mass ratio of electron q 2 VE BL21 1. The discovery of the electron Measure the charge to mass ratio of electron §26.1 Some important discoveries at the end of the 20th century 2 2 2 B L yE m q =