The measurement of the force acting between two parallel, current-carrying wires is known as Ampère's experiment. A mechanical balance was historically employed to measure that force. We report a simple experiment based on an electronic precision balance that is useful in clearly showing students the existence of this interaction and how to…

Students receive a more complete conception of scientific cognition methods if they reproduce fundamentally important historical investigations on their own. Ohm's investigation realized in 1826 is one of these. This paper presents a simple and accessible experimental unit, in which Ohm's ideas are implemented with the help of modern…

This paper deals with effects that appear on photographs of rotating objects when taken by a photo finish camera, a rolling shutter camera or a computer scanner. These effects are very similar to Roget's palisade illusion. A simple quantitative analysis of the images is also provided. The effects are explored using a computer scanner in a way that…

The speed of light, or more generally, the speed of electromagnetic waves, seems to be incredibly high. 300 000 km s[superscript -1] is far greater than the typical speed of a car, a plane or even a rocket, which is just several kilometres per second. It is thus natural that we treat the speed of light as infinite in everyday life. It appears,…

Teaching prismatic colours usually boils down to establishing the take-home message that white light consists of "differently refrangible" coloured rays. This approach explains the classical spectrum of seven colours but has its limitations, e.g. in discussing spectra from setups with higher resolution or in understanding the well…

In this paper an example of a simple harmonic motion, the apparent motion of sunspots due to the Sun's rotation, is described, which can be used to teach this subject to high-school students. Using real images of the Sun, students can calculate the star's rotation period with the simple harmonic motion mathematical expression.

We describe the use of Apple's iPod touch/iPhone, acting as the pendulum bob, as a means of measuring pendulum period, making use of the device's three-axis digital accelerometer and the freely available SPARKvue app from PASCO scientific. The method can be readily incorporated into an introductory physics laboratory experiment.…

We use a tablet to experimentally determine the dependencies of the magnetic field (B) on the electrical current and the axial distance from a coil (z). Our data shows good precision on the inverse cubic dependence of the magnetic field on the axial distance, B?z[superscript -3]. We obtain the value of air permeability µ[subscript air] with good…

The effectiveness of a refutational text in addressing the alternative conceptions held by secondary school students on the topic of wave propagation in an elastic medium was explored in this study. The refutational text, which was 816 words long and featured the particle-spring model, was found to be more effective in promoting conceptual change…

Studies have shown that standard lectures and instructional laboratory experiments are not effective at teaching interference and diffraction. In response, the author created an interactive computer program that simulates interference and diffraction effects using the finite difference time domain method. The software allows students to easily…

We present a simple and accurate experiment to obtain the speed of sound in air using a conventional speaker and a microphone connected to a computer. A free open source digital audio editor and recording computer software application allows determination of the time-of-flight of the wave for different distances, from which the speed of sound is…

Details are given for the conversion of an inexpensive webcam to a camera specifically sensitive to the near infrared (700-1000 nm). Some experiments and practical applications are suggested and illustrated. (Contains 9 figures.)

A unit aiming to introduce pre-service teachers of primary education to the limited predictability of deterministic chaotic systems is presented. The unit is based on a commercial chaotic pendulum system connected with a data acquisition interface. The capabilities and difficulties in understanding the notion of limited predictability of 18…

The Newtonian force concept is very difficult for introductory students to learn. One obstacle to learning is a premature focus on gravity-driven motions, such as vertical free fall, rolling motion on an inclined plane, and the Atwood's machine. In each case, the main agent of motion ("gravity") cannot be seen, heard, or controlled by the student.…

This article describes a few simple experiments that are worthwhile for slow motion recording and analysis either because of interesting phenomena that can be seen only when slowed down significantly or because of the ability to do precise time measurements. The experiments described in this article are quite commonly done in Czech schools. All…