An electric motor converts electrical energy into mechanical work and an electric generator converts mechanical work into electrical energy. The symmetry between the motor and generator naturally leads to questions about creating a perpetual motion machine. The allure of this question has inspired textbook problems, physics education articles, and…

This paper describes simple modifications to a demonstration Stirling engine that allows one to make quantitative measurements of the Stirling cycle. First, we describe measurements of the "P-V" diagram using an in-expensive pressure sensor and a common photogate. Then, as a supplement, the engine was run as a refrigerator by using a…

In this work, an easy-to-set-up demonstration about electromagnetic induction is presented, where a simple toy electric motor is transformed into a musical instrument. With this creative way to mix physics and music, it is expected to engage and motivate students to learn about the basic concepts of electromagnetism.

Previous generations of physics students learned how common machines work, as evidenced by their textbook illustrations. Such understanding of machines that daily life depends on seems to be evaporating. In response, for two decades I have conducted an introductory physics "engine cadaver lab." It offers opportunities for hands-on…

With the rapid spread of high-speed railway technology, there is a resurgence of interest in trains and railways. The main propulsive engine for railways was the steam engine for over a century, which gave way to the diesel and electrical engines. The steam engine was crucial to the birth and development of the railway industry, and understanding…

The most common type of homopolar motor comprises a cylindrical neodymium magnet, a battery, and a non-ferromagnetic frame rotating around the battery. Here, the author substituted a coiled spring for the frame. Due to this change, a new and intriguing effect emerges, the axial buzzing of the spring during its rotation. This paper describes the…

Although we may consider the power outlets in our homes to be nearly ideal voltage sources, a variety of influences in and around the home can cause departures from the nominal 60 Hz, 110-120 V root-mean-square (rms) of the North American grid. Even without instrumentation, we can see that a large motor starting from rest can be sufficient to…

An essential laboratory exercise for our lower-division electromagnetism course involves the measurement of Earth's local magnetic field from the emf induced in a rotating coil of wire. Although many methods exist for the measurement of Earth's field, this one gives our students some practical experience with Faraday's law. The apparatus we had…

Two students in a recent thermodynamics/statistical mechanics course needed to complete a course-related project to receive honors credit for the class. Such courses are typically theoretical, without an accompanying laboratory, although there are existing related hands-on exercises. The choice of the project was influenced by one student's desire…

The ability of our society to make informed energy-usage decisions in the future depends partly on current science and engineering students retaining a deep understanding of the thermodynamics of heat engines. Teacher imaginations and equipment budgets can both be taxed in the effort to engage students in hands-on heat engine activities. The…

Thermo dynamic cycles in introductory physics courses are usually made up from a small number of permutations of isothermal, adiabatic, and constant-pressure and volume quasistatic strokes, with the working fluid usually being an ideal gas. Among them we find the Carnot, Stirling, Otto, Diesel, and Joule-Brayton cycles; in more advanced courses,…

It's common knowledge that light can produce chemical and electronic changes (photography is based on those effects); however, many people consider light to have no mechanical effect. Some are familiar with the novelty of a radiometer that spins when placed in the light. Fewer are aware that a cymbal will vibrate audibly if hit by the light from a…

As a physics teacher I like recycling old apparatus and using them for demonstrations in my classes. In physics laboratories in schools, sources of high voltage include induction coils or electronic systems that can be bought from companies that sell lab equipment. But these sources can be very expensive. In this article, I will explain how you…

The St. Louis Motor, invented in 1909, is unique among physics apparatus for being named for a geographical place rather than a physicist. The sturdy little device (Fig. 1) has never been out of production. Any older school or physics department that has not done a catastrophic housecleaning in the last 20 years will certainly have a small flock…

Have you ever put your hand on an electric motor or motor-driven electric appliance and felt it vibrate? Ever wonder why it vibrates? What is there about the operation of the motor, or the object to which it is attached, that causes the vibrations? Is there anything "regular" about the vibrations, or are they the result of random causes? In this…