Jj thomson atomic model cathode ray experiment

Jj thomson atomic model cathode ray experiment series#

German researchers were convinced that the cathode rays traveled in waves, like light, whereas the British researchers thought that the rays were composed of tiny, tiny charged particles. Since Faraday had called the negative pole or plate the cathode, Goldstein called his radiation, cathode rays. On the wall opposite to the negative cathode, the glass glowed a strange, greenish color.Д«y 1876 Eugen Goldstein was certain that the glow was being caused by a new kind of radiation that started at the negative plate and radiated across the vacuum until it hit the glass. His superior vacuum pump removed all the air from the tube, and he connected the anode and the cathode to the appropriate ends of a powerful battery.ДЄt high enough voltages electricity certainly seemed to be able to leap across the vacuum between the oppositely charged plates, but that was not all. His apparatus consisted of a glass tube in which an anode (the positive pole, or plate) was at one end, and the cathode (the negative pole, or plate) was at the other end. Unfortunately his methods of producing an appropriate vacuum were not good enough and he never really succeeded, but a German glass blower - Heinrich Geissler - certainly did. He also got the idea to pass an electrical current (discharge) through a complete vacuum, just to see what happened - if anything. Using this technique, he discovered many things, including new elements, and aroused the interest of his pupil - Michael Faraday (1792 - 1867).ДЇaraday coined many of the terms still used today, including electrolysis, electrolyte, electrodes, anode, anions, cathode and cations. The English chemist Humphrey Davy (1778-1829) had built the world's largest battery (over 250 metallic plates) and pushed the very high currents this battery could generate through all kinds of solutions, compounds and substances in the hope that the high energies involved would pull apart the chemical constituents. This process is experimental and the keywords may be updated as the learning algorithm improves.In the 1800s electricity was new, exciting and the subject of a lot of study. These keywords were added by machine and not by the authors. This period of the history of structure of the atom has been the subject of considerable debate and controversy in the history and philosophy of science literature (Achinstein, 1991 Falconer, 1987 Heilbron, 1985 Heilbron & Kuhn, 1969 Hettema, 1995 Holton, 1986, 1993 Jammer, 1966 Kuhn, 1984 Lakatos, 1970 Popper, 1965).

Bohr evolved in quick succession and had to contend with competing models based on rival research programs.

The history of the structure of the atom since the late nineteenth and early twentieth centuries shows that the models of J.J. This reminds us that almost 45 years ago we ignored Schwab's (1962) advice that science cannot be taught as an вЂњunmitigated rhetoric of conclusions in which the current and temporary constructions of scientific knowledge are conveyed as empirical, literal, and irrevocable truthsвЂќ (p.

Jj thomson atomic model cathode ray experiment series#

In contrast, most textbooks consider Bohr's major contribution to be the explanation of the Balmer and Paschen series of the hydrogen line spectrum (i.e., experimental findings). In the case of Bohr's research program, Lakatos (1970) considers Bohr's explanation of the paradoxical stability of the Rutherford atom as the heuristic principle. This rationale, which helped Thomson to identify cathode rays as ions or universal charged particles (rival hypotheses), precisely constitutes the вЂњheuristic principle.вЂќ In a recent study, Blanco and Niaz (1997b) have shown how both students and teachers understand Thomson's experiments as a series of conclusions based on empirical findings (truths). Although the experimental details are important we cannot ignore the rationale behind Thomson's determination of the charge to mass ratio of cathode rays. Thomson's experimental work with cathode rays. To understand the function of вЂњheuristic principlesвЂќ let us consider J.J. Matthews (1994) emphasized the importance of heuristic principles in scientific inquiry and science education in similar terms. Monk and Osborne (1997) pointed out how many science curricula have forgotten Schwab's important epistemological distinction between the methodological (experimental data) and interpretative (heuristic principles) components. It tells us what meaning to assign these factsвЂќ (Schwab, 1974, p. In other words: вЂњA fresh line of scientific research has its origins not in objective facts alone, but in a conception, a deliberate construction of the mind вЂ¦ this conception вЂ¦ tells us what facts to look for in the research. According to Schwab (1974) scientific inquiry tends to look for patterns of change and relationships which constitute the heuristic (explanatory) principles of our knowledge.