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We present a simple circuit that performs Fermi-Dirac integration. The core of the circuit is a differential amplifier that we show is a model of a Fermi-Dirac system. The construction and characterization of the circuit requires students to apply knowledge of device physics, transistor circuit theory, and signal processing. The circuit construction is relatively simple and requires only a few components found in most electronics laboratories. (c) 2005 American Association of Physics Teachers. [DOI: 10.1119/1.1938951]

We discuss the two-capacitor problem found in many introductory physics texts in which there appears to be missing energy in an ideal, zero-resistance circuit, following the sudden charging of one capacitor from another. The paradox of this missing energy is traditionally ascribed to finite-resistance wires, the initial assumption of an ideal circuit and the rapid nature of the charging notwithstanding. By treating radiative effects in the simplest approximation, we show that the paradox is really nothing more than an inappropriately applied lumped-parameter model. In particular, we show that in the zero-resistance circuit, radiation fully accounts for all of the energy lost. To explore radiative effects in more realistic circuits, we also discuss numerical examples that include a small resistance and inductance. [DOI: 10.1119/1.1435344]

The construction and operation of inexpensive heat pipe ovens that facilitate optical experiments requiring a high vapor pressure in the material to be studied and two experiments using the ovens are given. One experiment explores the effect of increasing vapor density by measuring the adsorption of white light in potassium vapor at different temperatures while another examines the vibrational structure in molecular emissions through laser spectroscopy.