# Cathode Ray Experiment Research Paper

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Ordinary observations were a key to new discoveries which later led to the discoveries in the 1800s. The vacuum pump, which was a tube with electricity passed through with only some air particles, was a large part of finding and studying the relationship between charge and mass. There were metal electrons that were attached on the opposite sides of the tube, and the negative terminal of the battery is the cathode, and the anode is the positive terminal. While Sir William Crookes was experimenting, he saw a ray of light going through the tube. Later, it was discovered that it was radiation that was traveling from the negative terminal, the cathode, to the positive terminal, the anode. This ray is known as the cathode ray now. From this discovery,…show more content…
However, an English physicist J.J Thomson started several different cathode ray experiments in order to find out the ration of the charge to the mass of the particles. After a series of experiments, he was able to determine this by measuring the effect of an electric field and a magnetic field on a cathode ray. After comparing this ratio to other ratios, he was able to conclude that a hydrogen atom, which is the lightest atom, was heavier than the mass of a charged particle. This was a very surprising result because nobody knew about smaller particles than an atom. Therefore, Dalton's idea of an inseparable atom was wrong; there were subatomic particles. Since everyone believed Dalton's ideas, many were not able to believe this idea. However, with this experiment, Thomson was able to be the first one to discover the electron.

The charge of an electron was determined in 1909 by Robert Millikan, an American physicist. Now, the charge he measured nearly 100 years ago is accepted within 1% of our current value. This means that one electron has a charge of 1-. Through the use of the charge-to-mass ratio, Millikan was able to determine the mass of an electron: 9.1 X 10^-28g = 1/1840 mass of a hydrogen