The stately fall of magnets through conducting pipes is a favorite classroom and laboratory activity used in teaching electromagnetic induction, Lenz's law, eddy currents, electromagnetic braking, and even Newton's third law. When a neodymium magnet is used, the terminal velocity is reached in just a few milliseconds as the induced eddy currents…

The question of how the processes around the Faraday generator with its rotating magnet should be interpreted has been controversial since its discovery by Faraday. Does the magnetic field rotate together with the rotating magnet or does it remain stationary? Furthermore, does one only need Faraday's flux law to interpret inductive processes, or…

The magnetic field of Earth, B[subscript e], is an intriguing topic in the introductory physics curriculum that engages students' curiosity and inspires numerous speculations about the nature of this phenomenon. There are several methods for measuring Earth's magnetic field. Probably, the most widespread and visual method of measuring the field in…

In a 1993 book review, E. Pearlstein asks, "Why don't textbook authors begin their discussion of magnetism by talking about magnets? That's what students have experience with." A similar question can be asked, "Why don't professors have students measure the force between permanent magnets in introductory physics labs?" The…

The Gaussian gun is an arrangement of magnets and ball bearings (pictured in Fig. 1) such that--when the leftmost ball is released--the rightmost ball is ejected at high speeds. The device has been described in several articles on energy education. The sudden appearance of kinetic energy offers a productive context for considering a range of…

In the teaching and learning of physics, simulations have many applications. Simulations can help to illuminate concepts (such as the motion of electrons in electric or magnetic fields) that cannot usually be seen with the unaided eye, or to slow down things that happen over short time periods or at high speeds. They can also be used to help…

This paper describes a pictorial approach to Lenz's law that involves following four steps and drawing three pictures to determine the direction of the current induced by a changing magnetic flux. Lenz's law accompanies Faraday's law, stating that, for a closed conducting loop, the induced emf (electromotive force) created by a changing magnetic…

The internal sensors in smartphones for their advanced add-in functions have also paved the way for these gadgets becoming multifunctional tools in elementary experimental physics. For instance, the acceleration sensor has been used to analyze free-falling motion and to study the oscillations of a spring-mass system. The ambient light sensor on…

In introductory physics laboratories, spring constants are traditionally measured using the static method. The dynamic method, via vertical spring-mass oscillator, that uses a stopwatch in order to measure the period of oscillations is also commonly employed. However, this time-measuring technique is prone to human errors and in this paper we…

A magnetic linear accelerator (or Gauss accelerator) is a device that uses the conversion of magnetic energy into kinetic energy to launch an object with high velocity. A simple experimental implementation consists of a line of steel spheres in which the first one is a permanent magnetic sphere. If another steel ball collides with the magnetic…

I describe an easy-to-build instrument for illustrating the Lorentz force and measuring magnetic fields in introductory physics labs.

The typical friction lab performed in introductory mechanics courses is usually not the favorite of either the student or the instructor. The measurements are not all that easy to make, and reproducibility is usually a troublesome issue. This paper describes the augmentation of such a friction lab with a study of the viscous drag on a magnet…

The 1990 film "The Hunt for Red October" (based on Tom Clancy's 1984 debut novel of the same name) featured actors like Sean Connery and Alec Baldwin, but the star of the movie for physicists was a revolutionary new magnetohydrodynamic (MHD) marine propulsion system. The so-called "caterpillar drive" worked with no moving…

Barlow's wheel has been a favorite demonstration since its invention by Peter Barlow (1776-1862) in 1822. In the form shown in Fig. 1, it represents the first electric motor. The interaction between the electric current passing from the axle of the wheel to the rim and the magnetic field produced by the U-magnet produces a torque that turns…

As presented in physics textbooks, as well as in a few papers, the typical example of an induced motional electromotive force e[subscript mot] = "Blv" consists of a conductive rod of length "l" frictionlessly sliding with speed v along parallel wires within an orthogonal and constant uniform magnetic field of magnitude…