Einstein's Hypothesis Research Articles

The Sutherland–Einstein Hypothesis on the Origin of Magnetic Fields of Astropysical Objects

The Sutherland–Einstein Hypothesis on the Origin of Magnetic Fields of Astropysical Objects

Development and Students’ Perception on Teaching Aids of Photoelectric Effect Experiment Using Leds

The photoelectric effect experiment generally uses a very sophisticated and expensive apparatus. Some high schools and even universities in Indonesia cannot afford to conduct this experiment because of the high price of the apparatus. The purpose of this study was to develop a user-friendly, and cost-effective teaching aids which can be used to demonstrate the concepts of modern physics related to the photoelectric effect. The stages of this study employed the Four-D model, namely define, design, develop, and disseminate. Based on experts and practitioner evaluation, the developed teaching aids and practicum devices of photoelectric effect experiment were found to be valid and reliable. The results of the experiment by using this developed teaching aids of the photoelectric effect showed that there is a linear relationship between the stopping potential and the frequency of light emitted by the LED. These results are consistent with Millikan's experimental results, the first physicist who succeed in proving Einstein's hypothesis of the photoelectric effect, that in the photoelectric effect the stopping potential does not depend on the intensity of light but depends only on the frequency of light. In this study, the Planck’s constant value obtained is 6.408x10-34 J.s. Although this value is slightly smaller than the accepted value of Planck's constant that is 6.626x10-34 J.s, it is good enough considering the instrumental error occurred during the measurement of current and voltage. Furthermore, the students’ perception of the developed teaching aids and practicum devices of the photoelectric effects experiment are 74.9% (good) and 80.2% (very good), respectively. This indicates that the photoelectric effect experiment teaching aids and practicum devices that have been developed can be used to demonstrate and prove the concepts of modern physics related to the photoelectric phenomena correctly.Keywords: Teaching Aids, Photoelectric Effect, Students’ Perception

Experimental study on the validity of flow region division

Einstein first proposed that a river flow can be divided into three parts, corresponding to the banks and its bed, respectively, but he did not explain why the flow is dividable and how to divide the flow, in other words the flow division is only a mathematical treatment to simplify his analysis. Since Einstein's proposition there have been many researches and debates on this topic, many division lines have been proposed, but there is no specially designed experimental research to verify the physical existence of division lines, and these division lines have not been tested against the experimental data. For this purpose, an experiment in a rectangular open channel was conducted to measure whether zero-shear stress exists in an open channel except its existence on the free surface. The measured results reveal that zero-shear stress indeed exists below the free surface, and some proposed equations of division line agree well with the profile of the measured zero-shear line, thus it is clarified that Einstein's hypothesis is not only useful to simplify the mathematical treatment, but also it has the physical basis, i.e., zero-shear division line. As far as the authors know, in the literature, this is the first experimental proof that the division lines indeed exist in channel flows.

William H. Bragg's Corpuscular Theory of X-Rays and γ-Rays

The modern corpuscular theory of radiation was born in 1905 when Einstein advanced his light quantum hypothesis; and the steps by which Einstein's hypothesis, after years of profound scepticism, was finally and fully vindicated by Arthur Compton's 1922 scattering experiments constitutes one of the most stimulating chapters in the history of recent physics. To begin to appreciate the complexity of this chapter, however, it is only necessary to emphasize an elementary but very significant point, namely, that while Einstein based his arguments for quanta largely on the behaviour of high-frequency black body radiation or ultra-violet light, Compton experimented with X-rays. A modern physicist accustomed to picturing ultra-violet light and X-radiation as simply two adjacent regions in the electromagnetic spectrum might regard this distinction as hair-splitting. But who in 1905 was sure that X-rays and γ-rays are far more closely related to ultra-violet light than to α-particles, for example ? This only became evident after years of painstaking research, so that moving without elaboration from Einstein's hypothesis to Compton's experiments automatically eliminates from consideration an important segment of history—a segment in which a major role was played by William Henry Bragg.