Answer to Question #118749 in General Chemistry for Christina

Question

In Thomson's cathode-ray experiment, what evidence led him to believe that the ray consisted of particles, and why did he conclude that the ray was negatively charged?

Answer 1

Solution.

Thomson's experience consisted of studying beams of cathode rays passing through a system of parallel metal plates that created an electric field, and coil systems that created a magnetic field. During the experiment, it was found that the rays were deflected by the action of both fields separately, and at a certain ratio between them, the beams did not change the straight trajectory. The ratio of the fields depended on the speed of the particles. After making a series of measurements, Thomson found that the speed of particles is much lower than the speed of light — thus it was shown that the particles must have mass.

Answer:

Thomson's experience consisted of studying beams of cathode rays passing through a system of parallel metal plates that created an electric field, and coil systems that created a magnetic field. During the experiment, it was found that the rays were deflected by the action of both fields separately, and at a certain ratio between them, the beams did not change the straight trajectory. The ratio of the fields depended on the speed of the particles. After making a series of measurements, Thomson found that the speed of particles is much lower than the speed of light — thus it was shown that the particles must have mass.