This case study uses a daily cooking scenario to demonstrate how the boiling point of water is directly related to the external pressures in order to reinforce the concepts of boiling and boiling point, apply ideal gas law, and relate chemical reaction rates with temperatures. It also extends its teaching to autoclaves used to destroy…

A demonstration was created to display the unique behavior of a familiar element, phosphorus, and to make chemistry more accessible to the introductory student. The common allotropes of phosphorus and their reactivity are discussed. In this demonstration, the white allotrope of phosphorus is synthesized from the red phosphorus obtained from a…

Temperature and entropy traditionally are expressed in units of kelvin and joule/kelvin. These units obscure some important aspects of the natures of these thermodynamic quantities. Defining a rescaled temperature using the Boltzmann constant, T' = k[subscript B]T, expresses temperature in energy units, thereby emphasizing the close relationship…

In this article we propose a simple and low-cost experimental set-up through which science educators can demonstrate the Seebeck effect using a thermocouple and an instrumentation amplifier. The experiment can be set up and conducted during a 1-hour laboratory session. (Contains 3 tables and 3 figures.)

The hydromonochord is a horizontal vibrating string that just makes contact with the surface of a water bath. The motion of the string sets up a pattern of swirls on the surface of the water, thus complementing the usual pattern of nodes and antinodes. The device is based on the traditional monochord. A water basin (Fig. 1) has two slits in the…

A mirage can occur when a continuous variation in the refractive index of the air causes light rays to follow a curved path. As a result, the image we see is displaced from the location of the object. If the image appears higher in the air than the object, it is called a "superior" mirage, while if it appears lower it is called an "inferior"…

In the "The Science Study Series" book "The Physics of Television", it is stated that persistence of vision lasts for about a tenth of a second. This will be a notional figure just as 25 cm is taken to be the least distance of distinct vision. Estimates range from 1/8 to 1/16 s.

It's both surprising and rewarding when an old, standard problem reveals a subtlety that expands its pedagogic value. I realized recently that the role of gravity in the range equation for a projectile is not so simple as first appears. This realization may be completely obvious to others but was quite new to me.

Even though the buoyancy force (also known as the Archimedes force) has always been an important topic of academic studies in physics, its point of application has not been explicitly identified yet. We present a quantitative approach to this problem based on the concept of the hydrostatic energy, considered here for a general shape of the…

The time-average power radiated by a pair of infinitesimal dipoles is examined as their spacing is varied. The results elucidate the effect of the interaction of the dipoles on their radiation. (Contains 4 figures.)

A basketball bounced on a stiff surface produces a characteristic loud thump, followed by a high-pitched ringing. Describing the ball as an inextensible but flexible membrane containing compressed air, I formulate an approximate theory of the generation of these sounds and predict their amplitudes and waveforms. (Contains 3 figures.)

A coherer is a bistable device based on metal filings loosely confined between solid metal electrodes. This granular material normally exhibits a very high electrical resistance (tens of kilohms), but passage of the high-frequency current generated by reception of a radio signal causes it to "cohere" into a comparatively low resistance condition…

Great scientists in the past have experimented with coils and magnets. Here we have a variation where coupling occurs between two coils and the oscillatory motion of two magnets to give somewhat surprising results. (Contains 6 figures and 1 footnote.)

In this work, an inexpensive 10-gallon glass aquarium was used to study wave motion in water. The waves travel at speeds comparable to a person walking ([approximately]1 m/s). The scale of the motion allows for distances to be measured with a meterstick and for times to be measured with a stopwatch. For a wide range of water depths, standing waves…

On January 29, Mars will reach opposition, a point along its orbit around the Sun where Mars will be directly opposite from the Sun in a two-planet and Sun line-up with the Earth in between. At this opposition, the Earth and Mars will be separated by nearly 100 million km. An opposition is similar to a full Moon in that the planet at opposition…