4.2 The Electron Was the First Subatomic Particle Discovered

The Cathode Ray Tube

The nature of a cathode ray tube is discussed. The ray behaves as a series of charged particles racing from one electrode to the other. These particles are deflected by a magnet. The angle of deflection depends on the charge of these particles and their mass. Duration: 6:54.

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The Oil Drop Experiment

Millikan's oil drop experiment is used to determine the value of the fundamental unit of charge. Knowing this value, scientists were able to calculate the mass of the cathode ray particles, which turned out to have less mass than the smallest known atom. Duration: 6:25.

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