Modern Physics

Eugen Goldstein: Discoveries and Contributions

Eugen Goldstein was one of the leading German physicists, born in present-day Poland in 1850. His scientific work encompasses experiments with electrical phenomena in gases and cathode rays.

Goldstein identified the existence of protons as equal and opposite charges to electrons. This discovery was made by experimenting with cathode ray tubes in 1886.

The electron beam is directed from the cathode to the anode.

One of his most prominent legacies was the discovery of what are now known as protons, along with channel rays, also known as anode or positive rays.

Was there an atomic model of Goldstein?

Godlstein did not propose an atomic model, although his discoveries allowed the development of the Thomson atomic model.

On the other hand, he is sometimes credited with discovering the proton, which I observe in the vacuum tubes where he observed cathode rays. However, Ernest Rutherford is considered the discoverer in the scientific community.

Cathode ray experiments

Crooke tubes

Goldstein began his experiments with Crookes tubes during the 70s. He then made modifications to the structure developed by William Crookes in the 19th century.

The base structure of the Crookes tube consists of an empty glass tube, inside which the gases circulate. The pressure of gases inside the tube is regulated by moderating the evacuation of air inside it.

The device has two metal parts, one at each end, which act as electrodes, and the two ends are connected to external voltage sources.

When electrifying the tube, the air is ionized and becomes a conductor of electricity. Consequently, the gases become fluorescent when the circuit between the two ends of the tube is closed.

Crookes concluded that this phenomenon was due to the existence of cathode rays, that is, electron flow. With this experiment, the existence of elementary particles with a negative charge in atoms was demonstrated.

Modification of Crookes Tubes

Goldstein modified the structure of the Crookes tube and added several perforations to one of the tube’s metallic cathodes.

In addition, he repeated the experiment with the modification of the Crookes tube, increasing the voltage between the ends of the tube to several thousand volts.

Under this new configuration, Goldstein found that the tube emitted a new glow starting from the end of the tube that had been drilled.

However, the highlight is that these rays moved in the opposite direction to cathode rays and were called channel rays.

Goldstein concluded that, in addition to the cathode rays, which traveled from the cathode (negative charge) to the anode (positive charge), there was another ray traveling in the opposite direction, that is, from the anode to the tube’s modified cathode.

Furthermore, the behavior of particles in relation to their electric field and magnetic field was totally opposite to that of cathode rays.

This new flow was named by Goldstein as channel rays. Since the channel’s rays were traveling in the opposite direction to the cathode rays, Goldstein deduced that the nature of their electrical charge must also be opposite. That is, the rays in the channel had a positive charge.

channel rays

Channel rays arise when cathode rays collide with atoms of the gas that is confined within the test tube.

Equally charged particles are repelled. From that base, the electrons from the cathode rays repel the electrons from the gas atoms, and these shed their original formation.

Gas atoms lose their negative charge and are positively charged. Such cations are attracted to the negative tube electrode, given the natural attraction between opposite electrical charges.

Goldstein dubbed these rays “Kanalstrahlen” to refer to the counterpart of cathode rays. The positively charged ions that make up the channel rays move towards the perforated cathode until it passes through, given the nature of the experiment.

Therefore, this type of phenomenon is known in the scientific world as channel rays, as they pass through the perforation existing in the cathode of the study tube.

Modification of cathode tubes

Likewise, Eugen Godlstein’s essays also contributed significantly to the deepening of technical notions about cathode rays.

Through experiments in evacuated tubes, Goldstein detected that cathode rays could cast sharp emission shadows perpendicular to the area covered by the cathode.

This discovery was very useful in modifying the design of the cathode tubes used until today and placing concave cathodes in the corners, to produce focused rays that would be used in various applications in the future.

In turn, the channel rays, also known as anode or positive rays, depend directly on the physicochemical characteristics of the gas contained in the tube.

Consequently, the relationship between the electrical charge and the mass of the particles will be different depending on the nature of the gas used during the experiment.

With this conclusion, it was clarified the fact that the particles exit from the interior of the gas, and not from the anode of the electrified tube.

Goldstein’s Contributions

First steps in proton discovery

Based on the certainty that the electrical charge of atoms is neutral, Goldstein took the first steps to verify the existence of positively charged fundamental particles.

Fundamentals of Modern Physics

Goldstein’s research work brought with it the foundations of modern physics, as the demonstration of the existence of channel rays made it possible to formalize the idea that atoms moved quickly and with a specific pattern of motion.

This type of notion was fundamental in what is now known as atomic physics, that is, the field of physics that studies the behavior and properties of atoms as a whole.

isotopic study

Thus, Goldstein’s analysis gave rise to the study of isotopes, for example, among many other scientific applications that are fully valid today.

However, the scientific community attributes the discovery of the proton to New Zealand chemist and physicist Ernest Rutherford in mid-1918.

The discovery of the proton, as the counterpart of the electron, laid the foundations for building the atomic model we know today.

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