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Conference: Physics brings the community together Training: CERN trains physics teachers Education: World conference fosters physics collaborations Lecture: Physics education live at ASE Prize: Physics teacher wins first Moore medal Festival: European presidents patronize Science on Stage festival Videoconference: Videoconference brings Durban closer to the classroom

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This article was authored by Alastair Reid and Ronan McDonald, not solely by Alastair Reid. The publisher apologizes for this omission.

This paper revisits a well-known hydrostatic paradox, observed when turning upside down a glass partially filled with water and covered with a sheet of light material. The phenomenon is studied in its most general form by including the mass of the cover. A historical survey of this experiment shows that a common misunderstanding of the phenomenon has recently arisen.

A lens based on liquid in the confined volume of a volumetric flask was presented as a potential projector to observe microscopic floating organisms or materials. In this experiment, a mosquito larva from a natural pond was selected as a demonstration sample. By shining a light beam from a laser pointer of any visible wavelength through the volumetric flask filled with liquid, the movements of floating objects were clearly observed on a screen. The magnification was simply controlled by changing either the volume of the flask or the distance of the screen from the flask.

New undergraduate students arriving to study physics at the University of Bristol from 1975 onwards have all taken the same test of their knowledge and understanding of physics and mathematics. Many of the questions test knowledge of material that has been in the A-level syllabus for maths or physics throughout this period. The ability of incoming students to answer these questions declined significantly in the 1990s with average scores falling from around 75% up to 1990 to below 50% after 2000 against a background of increasing A-level grades of the entrants to the programme. It is suggested that changes in teaching and examination methods have caused students to be less able to carry out multi-stage calculations and that the introduction of modular examinations may have encouraged a culture where students tend to forget material learnt in previous modules.

This article discusses an instructional strategy which explores eventual similarities and/or analogies between familiar problems and more sophisticated systems. In this context, the Atwood's machine problem is used to introduce students to more complex problems involving ropes and chains. The methodology proposed helps students to develop the ability needed to apply relevant concepts in situations not previously encountered. The pedagogical advantages are relevant for both secondary and high school students, showing that, through adequate examples, the question of the validity of Newton's second law may even be introduced to introductory level students.

In this paper we report on the use of two different light to frequency converters, four different light sources, three of which are novel and inexpensive, and a hand held digital multimeter with a frequency counter, suitable for making accurate and rapid determination of the optical inverse square law exponent of − 2 to better than ± 0.005 over more than a factor of 100 in distance and a factor of 5 × 10⁵ variation of light intensity. Accurate data sets can be taken in 20–40 min, typically one minute per data point or less. The wide range of intensities measured makes a convincing demonstration of the optical inverse square law, and forms the basis for students learning how to plot log–log graphs over multiple orders of magnitude, extract power law exponents and learn about coefficients of determination. The extremely low cost of this high accuracy experiment and the ease of its implementation are appropriate for even the most modest budgets and least equipped high school physics laboratories.

The use of a video camera may markedly improve demonstrations of optical spectra. First, the output electrical signal from the camera, which provides full information about a picture to be transmitted, can be used for observing the radiant power spectrum on the screen of a common oscilloscope. Second, increasing the magnification by the camera enhances the resolution of the spectra displayed by a colour monitor. In particular, it becomes possible to resolve the sodium doublet at 579 nm (Δλ = 0.6 nm).

In this work, we studied the rolling motion of solid and hollow cylinders down an inclined plane at different angles. The motions were captured on video at 300  frames s ^{− 1}, and the videos were analyzed frame by frame using video analysis software. Data from the real motion were compared with the theory of rolling down an inclined plane without slipping. From the experiment, the acceleration does not depend on the cylinder mass as indicated from the theory. For the wood–steel surface, we found that the coefficient of static friction was equal to 0.131 and the critical angle for the solid cylinder was 21.45°. The critical angle for the hollow cylinder depends on the inner and outer radius of the cylinder. Motion paths of a point on the hollow cylinder at small and large angles were shown to elucidate the pure rolling condition. Finally, we demonstrated that total mechanical energy was conserved during the pure rolling motion. This confirms that work done by the friction force is zero. We will use these results to design an interactive lecture demonstration on rolling without slipping.

The 'radioactive dice' experiment is a commonly used classroom analogue to model the decay of radioactive nuclei. However, the value of the half-life obtained from this experiment differs significantly from that calculated for real nuclei decaying exponentially with the same decay constant. This article attempts to explain the discrepancy and suggests modifications to the experiment to minimize this effect.

Across the world, freshwater is valued as the most critically important natural resource, as it is required to sustain the cycle of life. Evaporation is one of the primary environmental processes that can reduce the amount of quality water available for use in industrial, agricultural and household applications. The effect of evaporation becomes intensified especially during conditions of drought, particularly in traditionally arid and semi-arid regions, such as those seen in a number of countries over the past ten years. In order to safeguard against the influence of droughts and to save water from being lost to the evaporative process, numerous water saving mechanisms have been developed and tested over the past century. Two of the most successful and widely used mechanisms have included floating hard covers and chemical film monolayers. This article describes a laboratory based project developed for senior high school and first year university classes, which has been designed to introduce students to the concepts of evaporation, evaporation modelling and water loss mitigation. Specifically, these ideas are delivered by simulating the large scale deployment of both monolayers and floating hard covers on a small water tank under numerous user defined atmospheric and hydrodynamic conditions, including varying surface wind speeds and underwater bubble plumes set to changing flow rates.

The basic theory of radio broadcasting is discussed from an experimental point of view. First, concepts like wave modulation and tuning are explained with the use of instruments in the physics laboratory. Then, a very basic radio receiver is described and assembled, whose most important feature, like in the old 'crystal radios', is the absence of a power supply. Even if the underlying general concepts are usually described in general physics classes at high school and university, for students this setup is a practical example of the application of electromagnetic waves.

The purpose of this article is to describe the construction of a Sun clock and calendar (SCandC) that will allow an observer to not only see the time but also the symmetry properties of the Sun–Earth relative movement. A set of circles drawn on the SCandC will allow the observer to see their associated dates as well as to perform a visual interpolation between any pair of consecutive circles to estimate an intermediate date. By introducing the sunrise and sunset horizon lines in the SCandC the observer will be able to find the sunrise and sunset times during most of the year. The observer will also be able to appreciate the difference in time duration between the spring–summer and autumn–winter periods, as a consequence of Kepler's second law, as well as to observe that there is a small difference between the circle radii of equidistant dates from the solstices in the spring–summer versus autumn–winter periods as a consequence also of Kepler's second law. The equations derived in the present article will be tested against data from a particular lighthouse.

What follows are several investigations involving string musical instruments developed for and used in a Science of Sound & Light course. The experiments make use of a guitar, orchestral string instruments and data collection and graphing software. They are designed to provide students with concrete examples of how mathematical formulae, when used in physics, represent reality that can actually be observed, in this case, the operation of string musical instruments.

A simple experiment using low cost equipment for the determination of the density of granular materials, without immersing them in a liquid, is presented. It is based only on the ideal gas state equation, so it is a good experimental task for undergraduate and high school students.

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