Electro-magnetic scattering is studied in a waveguide with varying shape and crosssection. Furthermore, an impedance or admittance condition is applied to two of the waveguide walls. Under the condition that variations in geometry or impedance take place in only one plane at the time, the problem can be solved as a two-dimensional wave-scattering problems. By using newly developed numerical conformal mapping techniques, the problem is transformedinto a wave-scattering problem in a straight two-dimensional channel. A numerically stable formulation is reached in terms of transmission and reflection operators. Numerical results are given for a slowly varying waveguide with a bend and for one more complex geometry.

This study deals with the energy concept in the school subject of geography. The energy concept is complex, not least because it is treated in different contexts with different meanings. As a science teacher, you want to understand the students' learning about science concepts, also such learning that is outside their subject. The aim of the qualitative study is therefore to investigate how the energy concept is treated in the subject of geography in order to gain a deeper understanding of how science teaching and geography teaching can complement each other. Six social science teachers in middle school were interviewed about their use of the energy concept. Their statements were thematized and compared with the four key ideas about the energy concept that Duit highlights as central from a scientific perspective. Three key ideas could be identified in the teachers' descriptions of how they treat the energy concept in the subject of geography. Three themes could also be distinguished in the data. The study indicates that the energy concept is treated in the subject of geography with some base in energy transformation and energy transfer. That makes it possible to work interdisciplinary regarding the energy concept.