Noise in a dynamical system is usually regarded as a nuisance. However, in certain nonlinear systems the addition of noise in the system can give counterintuitive dynamics. An illustrative phenomenon is stochastic resonance (SR). In this paper we present, an experiment demonstrating stochastic resonance in a bistable electronic device: the tunnel diode. This experiment is suitable both as a lecture demonstration and for student investigations. We introduce the statistical properties of the noise and the physical picture of the SR phenomenon. We describe the experimental setup and present typical results.

No abstract

No abstract

NEW APPROACHES contents of the calorimeter. As a result. calculating an accurate latent heat value would not be possible, unless one were to measure the mass difference between the original and remaining contents during the vaporization stage. Two faxinating experiences came out of this project for our students. First, students were able to apply computer technology to a fairly standard experiment and develop it into a meaningful research project that integrated concepts from circuits and thermo-dynamics. Second. students were able to observe a physical phenomenon with their own eyes that is usually presented to them in textbooks only. Direct visual observation enables students to better understand physical phenomena and laws (Mokros and Tinker 1987, Linn and Songer 1991). which is why this experiment is such a valuable activity for a physics course. References Galloway 1 A and Wilson J F 1992 Measuring the mechanical equivalent of heat-electrically Phys Teacher 30 504-6 Linn M C and Songer N B 1991 Teaching thermodynamics to middle school students What are appropriate cognitive demands? J. Res. Sci. reaching 28 885-918 Mokros J R and Tinker R F 1987 The impact of microcomputer based labs on children's ability to interpret graphs J. Res. Sci. Teaching 24 369-83

The Rapid Communications section is intended for the accelerated publication of important new results. Since manuscripts »bmit«d to this section are given priority treatment both in the editorial of/ice and in production, authors should explain tn their submit«l letter why the work justt'ftes this special handling A . Rapid Communication should be no longer than 3&/z printed pages and must be accompanied by an abstract P.

No abstract

No abstract

No abstract