Here, we propose a simple method for measuring the built-in potential and its temperature dependence of a photodiode by a photosaturation technique. The experimental design facilitates both current-voltage and null voltage measurements as a function of white light intensity. This method gives the built-in potential directly; as a result its…

We apply several physical ideas to determine the steady temperature distribution in a medium moving with uniform velocity between two infinite parallel plates. We compute it in the coordinate frame moving with the medium by integration over the "past" to account for the influence of an infinite set of instantaneous point sources of heat in past…

Treatment of phenylacetic acid with 90% HNO[subscript 3] yields a product, I, whose observed melting point is 175-179 degrees C and whose equivalent weight is approximately 226 grams. Treatment of phenylacetic acid with 70% HNO[subscript 3] yields a product, II, whose observed melting point is 106-111 degrees C and whose equivalent weight is…

Two experiments are described in which students explore phase transitions and critical phenomena by obtaining compression isotherms of phospholipid monolayers using a Langmuir trough. Through relatively simple analysis of their data students gain a better understanding of compression isotherms, the application of the Clapeyron equation, the…

This article describes a simple and inexpensive laboratory exercise developed to understand the effect of pressure on phase equilibrium as described by the Clausius-Clapeyron equation. The only piece of equipment required is a pressure cooker adapted with a pressure gauge and a thermometer in the lid, allowing the measurement of the pressure and…

The different approaches to the generation of power from solar energy may be roughly divided into five categories: distributed collectors; central receivers; biomass; ocean thermal energy conversion; and photovoltaic devices. The first approach (distributed collectors) is the subject of this module. The material presented is designed to…

While the new movement in the teaching of physics--the study of the physics of daily life--is the keynote of the recent text-books, yet the laboratory manuals still adhere to the old method, leaving the presentation of material from everyday life to the text-book alone. It is the authors' belief that the manual as well as the text-book should be…

Designed to use simple materials that can be found in almost any household, this document provides elementary teachers and students with activities and worksheets that deal with basic scientific concepts. The activities are intended to help students form and test their own hypotheses. Each topic in the booklet is addressed through a simple…

This ninth grade student manual was developed to be used in conjunction with some of the experimental science activities described in the teacher's guide. It contains laboratory worksheets for: (1) measurement; (2) basic energy concepts; (3) heat energy; (4) light; (5) sound; (6) electricity; and (7) present and future energy resources. Additional…