In a familiar demonstration, a hoop and a solid disk of the same diameter and mass are started from rest at the top of an inclined plane and race to the bottom. The disk reaches the bottom with a larger speed than the hoop and arrives first. Why?

As I approach my 70th year in physics, let me tell my younger colleagues about my adventures with computation. When I was 14, my father gave me a slide rule because I appeared to be headed toward a career in physics. Since then, I have had experience with many other calculating devices.

The Phantom Bouquet is a venerable lecture demonstration that does a fine job of showing how a concave spherical mirror can form a real, inverted image. In the original demonstration, a brightly illuminated artificial rose is hung by its stem in front of a concave spherical mirror. The distance from the reflecting surface to the rose is somewhat…

The object on the right-hand side of Fig. 1 is the whistling mechanism of an old-fashioned tea kettle. This started me thinking about similar devices in which a thin blade of air strikes a sharp wedge and a resonator is used to pick out specific frequencies. This note tells how I went about using the frequency spectrum application on a smartphone…

Many of us are familiar with the demonstration of boiling water in a paper cup held over a candle or a Bunsen burner; the ignition temperature of paper is above the temperature of 100°C at which water boils under standard conditions. A more dramatic demonstration is melting tin held in a playing card. This illustration is from Tissandier's book on…

Some of you may remember the 1979 television series "Connections" that was written and narrated by James Burke, a British science writer. Burke's technique was to choose a number of seemingly unrelated ideas and show how they led to developments in science and technology. This is an enjoyable business, even if some of the connections…

This article is about a late 19th-century teacher of secondary school physics. I was originally interested in the apparatus that he sold. This led me to the physics books that he wrote, and these took me to his unusual ideas about ways to use laboratory time to introduce students to the phenomena of physics. More than 100 years later educational…

Charles Wheatstone's name was once familiar to students because they used his eponymous bridge to measure resistances. That usage seems to be disappearing--we all have access to digital ohmmeters--but the techniques that he developed for making electrical measurements can still be used with profit. Also, his work with measuring very short time…

Almost everyone "knows" that steam is visible. After all, one can see the cloud of white issuing from the spout of a boiling tea kettle. In reality, steam is the gaseous phase of water and is invisible. What you see is light scattered from the tiny droplets of water that are the result of the condensation of the steam as its temperature…

Physics students often have problems understanding waves. Over the years numerous mechanical devices have been devised to show the propagation of both transverse and longitudinal waves (Ref. 1). In this article an updated version of an early-20th-century transverse wave machine is discussed. The original, Fig. 1, is at Creighton University in…

During the AAPT summer meeting at Creighton University in 2011, Vacek Miglus and I took pictures of early apparatus at the Creighton physics department. The apparatus in the left-hand picture, shown with the spigot closed, appeared to be a liquid-level device: the water level was the same in both the narrow tube and the flaring glass vase.…

Recently the handsome little galvanometer (only 10 cm high) in Fig. 1 came into the Greenslade Collection. This is a design without a moving coil and, consequently, is very rugged. At the same time, John Daffron independently sent Tom Greenslade the picture of a similar galvanometer that he had made some years back and has been using for…

The Frahm resonance principle, in which resonating reeds indicate the frequency of mechanical or electrical oscillations, is a hardy perennial. In this note we will give some history, show some original apparatus, and show how it may be reproduced with relatively little effort.

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…

My academic ancestors in physics have called on me once more to tell you about the apparatus that they devised, and that many of you have used in your demonstrations and labs. This article is about apparatus named after François Arago, Heinrich Helmholtz, Leon Foucault, and James Watt.