Recent findings suggest that children with autism may be impaired in the perception of biological motion from moving point-light displays. Some children with autism also have abnormally high motion coherence thresholds. In the current study we tested a group of children with autism and a group of typically developing children aged 5 to 12 years of…

This Classroom Activity Connections paper describes an extension to the "JCE" Classroom Activity #68 "Turning on the Light". A number of additional common items that display fluorescence under UV light are described, including fruits, vegetables, and seashells. Two classroom extensions on fluorescence are also described. From these activities,…

Four pigeons were trained in a procedure in which concurrent-schedule food ratios changed unpredictably across seven unsignaled components after 10 food deliveries. Additional green-key stimulus presentations also occurred on the two alternatives, sometimes in the same ratio as the component food ratio, and sometimes in the inverse ratio. In eight…

The work presented here demonstrates the feasibility of using the single-mode fibers of an optical Internet network to deliver visible light between separate laboratories as a way to perform remote spectroscopy in the visible for teaching purposes. The coupling of a broadband light source into the single-mode fiber (SMF) and the characterization…

An advanced undergraduate laboratory experiment is outlined which uses a dye laser to map out the chromatic dispersion curve of a polymethyl methacrylate (PMMA) optical fibre. Seven different wavelengths across the visible spectrum are employed using five different dyes. The light pulse is split into two pulses, one to a nearby photodetector and…

We report on the physics around an incandescent lamp. Using a consumer-grade digital camera, we combine electrical and optical measurements to explore Planck's law of black-body radiation. This simple teaching experiment is successfully used to measure both Stefan's and Planck's constants. Our measurements lead to a strikingly accurate value for…

Problems on the dynamics of changing mass systems often call for the more general form of Newton's second law Fnet = dp/dt. These problems usually involve situations where the mass of the system decreases, such as in rocket propulsion. In contrast, this experiment examines a system where the mass "increases" at a constant rate and the net force…

The flashlight is a simple device that is composed of a lightbulb, usually two cells connected in series, a housing, a switch, and a reflector for the light. All flashlights essentially use these parts to complete a circuit that converts the stored chemical energy in the cells to light energy. In this lesson, students will take apart an…

In November 2009, the largest experiment in history was restarted. Its prime target is the Higgs particle--the last remaining undiscovered piece of our current theory of matter. We present a very simple way to introduce this topic to senior secondary school students, using a comparison with the refractive index of light.

The aim of this study was to analyze the effectiveness of the conceptual change approach, explicit reflective approach, and the course book by the Ministry of Education on the views toward the nature of science and conceptual change in the Light unit. Three study groups were selected from several seventh grade classes. Two of the three classes,…

On a partly sunny afternoon, a fourth-grade class at the Marietta Center for Advanced Academics in Marietta, Georgia, was gearing up to explore key concepts regarding the nature of light. Armed with translucent beads and white pipe cleaners, the classroom teacher asked each student to count eight beads and then encouraged them to closely observe…

A clear view of the ocean may be used to measure the radius of the Earth. To an observer looking out at the ocean, the horizon will always form some angle [theta] with the local horizontal plane. As the observer's elevation "h" increases, so does the angle [theta]. From measurements of the elevation "h" and the angle [theta],…

A simple circuit is created by the continuous flow of electricity through conductors (copper wires) from a source of electrical energy (batteries). "Completing a circuit" means that electricity flows from the energy source through the circuit and, in the case described in this month's problem, causes the light bulb tolight up. The presence of…

What colour is a shadow? Black, grey, or some other colour? This article describes how to use a digital camera to test the hypothesis that a shadow under a clear blue sky has a blue tint. A white sheet of A4 paper was photographed in full sunlight and in shadow under a clear blue sky. The images were analysed using a shareware program called…

Is light a ray, a wave, or a particle? Yes, yes, and yes. An article in this issue ("The Benefits of Scientific Modeling," p. 40) discusses the process of scientific modeling, and light is a great example of how modeling works. There are three viable models for light, each appropriate for different situations. The author will discuss the…