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Splitting the second: Designing a physics course with an emphasis on timescales of ultrafast phenomena 分秒必争：以超快现象的时间尺度为重点设计物理课程
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-24 DOI: 10.1119/5.0133767
Igor P. Ivanov
{"title":"Splitting the second: Designing a physics course with an emphasis on timescales of ultrafast phenomena","authors":"Igor P. Ivanov","doi":"10.1119/5.0133767","DOIUrl":"https://doi.org/10.1119/5.0133767","url":null,"abstract":"Timescales spanning 24 orders of magnitude smaller than one second can be studied experimentally, and each range is packed with different physical phenomena. This rich range of timescales offers a great context for an innovative undergraduate physics course which introduces modern physics and technology from an unconventional perspective. Based on the author's experience in lecturing on these topics to different audiences, this paper proposes a syllabus of a semester-long timescale-based undergraduate physics course.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141808660","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Computing the shape of planet Earth 计算地球的形状
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0145569
Stephen J. Norton
{"title":"Computing the shape of planet Earth","authors":"Stephen J. Norton","doi":"10.1119/5.0145569","DOIUrl":"https://doi.org/10.1119/5.0145569","url":null,"abstract":"It is often noted that the Earth is slightly oblate rather than spherical, but the calculation of the Earth's eccentricity can be challenging. Here, we calculate it by minimizing the sum of the Earth's gravitational potential energy and its centrifugal potential energy. The Earth's gravitational potential energy can be derived with the help of the Green's function of the Laplace operator in oblate spheroidal coordinates. Under the assumption of a homogeneous planet, we obtain an analytic relationship for the Earth's eccentricity that was first derived by Maclaurin in 1742 and is about 13 percent larger than the observed value. Better agreement with observation is obtained by assuming that the Earth's core is about twice the density of the mantle, which reduces the Earth's moment of inertia. This exercise can provide practice in analyzing gravitational systems in spheroidal coordinates; the problem may also be relevant for other gravitating and rotating bodies, such as stars and galaxies.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141712847","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Exploring counterclockwise thermodynamic cycles 探索逆时针热力学循环
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0152547
Randall D. Knight
{"title":"Exploring counterclockwise thermodynamic cycles","authors":"Randall D. Knight","doi":"10.1119/5.0152547","DOIUrl":"https://doi.org/10.1119/5.0152547","url":null,"abstract":"A common belief is that any closed, counterclockwise cycle on a pV diagram represents a refrigerator or heat pump. It has been established that this is not the case, but previous papers on this topic have made unnecessary assumptions about the temperatures of the energy reservoirs and about how the system exchanges energy with the reservoirs. Relaxing these assumptions leads to a wide array of unexpected behaviors. In some cases, the same pV cycle can be a heat pump, a cold pump, or a Joule pump simply by changing how the system is connected to the reservoirs. This paper explores the strange world of counterclockwise cycles.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141709498","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Maxwell and the development of electromagnetic theory 麦克斯韦与电磁理论的发展
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0183355
Alfred M. Bork
{"title":"Maxwell and the development of electromagnetic theory","authors":"Alfred M. Bork","doi":"10.1119/5.0183355","DOIUrl":"https://doi.org/10.1119/5.0183355","url":null,"abstract":"This article presents an unpublished manuscript by Alfred M. Bork that was written in 1976 as an introduction to a collection of Maxwell's papers on electromagnetism which was never published. It provides encouragement to the reader to study the original works of Maxwell on electromagnetism, and this encouragement is as timely today as in 1976.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141712712","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 2
Footnotes (and other editorial innovations) 脚注（及其他编辑创新）
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0221171
B. Parks
{"title":"Footnotes (and other editorial innovations)","authors":"B. Parks","doi":"10.1119/5.0221171","DOIUrl":"https://doi.org/10.1119/5.0221171","url":null,"abstract":"","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141702761","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Insight into the gas–liquid transition from the Berthelot model 从贝特洛模型透视气液转变
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0094686
Li-Qin Mi, Dandan Li, Shanshan Li, Zhong-Heng Li
{"title":"Insight into the gas–liquid transition from the Berthelot model","authors":"Li-Qin Mi, Dandan Li, Shanshan Li, Zhong-Heng Li","doi":"10.1119/5.0094686","DOIUrl":"https://doi.org/10.1119/5.0094686","url":null,"abstract":"We extend the parametric method developed for the van der Waals model by Lekner [Am. J. Phys. 50(2), 161–163 (1982)] to other equations of state, particularly the Berthelot model, thereby making the testing of these equations of state much faster and simpler. We systematically investigate important properties of first-order phase transitions in the Berthelot model. Thermodynamic properties near the critical point are discussed and the predictions of the Berthelot and van der Waals models are compared with experimental data. The Berthelot equation affords an improved fit to the density–temperature coexistence curve for many substances when compared to the van der Waals equation. A failure of the Berthelot model is its prediction of latent heat and heat capacities that are convex functions at lower temperatures. We also examine two modifications of the Berthelot equation of state that, like the van der Waals model, are also solvable by the parameter method. These, which we call the cPF and dPF models, reduce to the van der Waals and Berthelot models in different limits of their parameters. They give improved fits to the experimental data away from the critical point but involve an additional fitting parameter.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141713855","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Spin coating experiments and theory for undergraduate physics and engineering students—A connection to microfabrication 面向物理学和工程学本科生的自旋涂层实验和理论--与微加工的联系
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0169090
M. Foster, J. Mendoza Cortes, H. C. Mayer
{"title":"Spin coating experiments and theory for undergraduate physics and engineering students—A connection to microfabrication","authors":"M. Foster, J. Mendoza Cortes, H. C. Mayer","doi":"10.1119/5.0169090","DOIUrl":"https://doi.org/10.1119/5.0169090","url":null,"abstract":"Spin coating is a process by which thin and uniform layers of liquids are formed on substrates by rotation of the substrate at high speed. Production of these thin liquid layers, specifically using liquids called photoresists, is essential for photolithography in semiconductor and microelectronics processing whereby patterns are transferred and ultimately formed in layers on the substrate. With the surge in interest for increased domestic semiconductor processing capabilities, it makes sense that students in physics and engineering are provided with more knowledge of these processing techniques and how they rely on, among other things, traditional course work, and topics. Spin coating provides an excellent example to connect fluid dynamics with microfabrication. We present detailed experiments that can be performed in a college-level undergraduate laboratory, wherein students can explore both the variables appearing in a known model for spin coating in addition to investigating several of the variables related key assumptions used in the derivation of the model but which do not appear in the resulting equation.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141709175","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
The e/m experiment: Student exploration into systematic uncertainty e/m 实验：学生对系统不确定性的探索
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0190546
Nicholas P. Gray, Tanisha K. Rutledge, Leigh Parrott, Christopher A. Barns, K. Aptowicz
{"title":"The e/m experiment: Student exploration into systematic uncertainty","authors":"Nicholas P. Gray, Tanisha K. Rutledge, Leigh Parrott, Christopher A. Barns, K. Aptowicz","doi":"10.1119/5.0190546","DOIUrl":"https://doi.org/10.1119/5.0190546","url":null,"abstract":"In this work, we convert a common verification lab in the physics curriculum, measuring the charge-to-mass ratio of the electron (e/m), into an investigative lab on systematic uncertainty. The Bainbridge apparatus, commonly used to measure e/m, can have significant systematic uncertainties, leading to large discrepancies with the accepted value. Students were asked to quantify possible systematic uncertainties in the apparatus and correct them. Building upon each other's work from semester to semester, students characterized multiple sources of systematic uncertainty. Not only did the students learn about uncertainty analysis techniques that reveal systematic uncertainties, but they also dramatically improved the accuracy of the apparatus, reducing the discrepancy from 15% to 0.5%. This paper describes a pedagogical approach to exploring unknown systematic uncertainties in an intermediate laboratory setting and the student-learning benefits of such an approach. In addition, it provides detailed information about untangling and correcting the sources of systematic uncertainty in the Bainbridge apparatus.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141700140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
In this issue: July 2024 本期内容2024 年 7 月
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0221011
Jesse Kinder, C. Marrache-Kikuchi, Raina Olsen, B. Parks
{"title":"In this issue: July 2024","authors":"Jesse Kinder, C. Marrache-Kikuchi, Raina Olsen, B. Parks","doi":"10.1119/5.0221011","DOIUrl":"https://doi.org/10.1119/5.0221011","url":null,"abstract":"","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141705315","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
Torricelli's experiment and conservation of momentum 托里切利实验和动量守恒
IF 0.8 4区 教育学
American Journal of Physics Pub Date : 2024-07-01 DOI: 10.1119/5.0145991
D. Alvaro-Berlanga, R. Planet, A. Fernandez-Nieves
{"title":"Torricelli's experiment and conservation of momentum","authors":"D. Alvaro-Berlanga, R. Planet, A. Fernandez-Nieves","doi":"10.1119/5.0145991","DOIUrl":"https://doi.org/10.1119/5.0145991","url":null,"abstract":"Torricelli's law states that the speed of a fluid as it flows out of an orifice of a large reservoir open to the atmosphere is equal to 2gh, where g is the acceleration of gravity and h is the distance between the free surface of the fluid in the reservoir and the orifice. Obtaining the flow rate from this speed is not at all trivial, despite how simple the situation seems, as the fluid jet issued at the orifice does not have a constant cross section and the motion of the fluid near the orifice is not really known. Here, we use Torricelli's experiment as a practical way to illustrate how to properly apply the momentum balance equation to solve hydrodynamic problems. We compare the horizontal component of the force exerted by the container on the fluid using both momentum conservation and the integral of the stress tensor; this results in a contradiction that we use to review, after considering simple experimental results, the assumptions made during the calculations, to finally resolve the discrepancy and rationalize the intricacies of this every-day situation.","PeriodicalId":7589,"journal":{"name":"American Journal of Physics","volume":null,"pages":null},"PeriodicalIF":0.8,"publicationDate":"2024-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141692698","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"教育学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
引用次数: 0
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