This study aims to determine the student teachers' SMK knowledge about interaction of electric current and magnetic field and their misconceptions. This study was carried out with 26 fifth grade physics student teachers attending teacher certificate program in 2007-2008 academic year in the Fatih Faculty of Education, employing case study. A subject matter test is used as data gathering tool. The data revealed that trainees have some problems with application of right-hand rule, finding direction of magnetic field and magnetic forces. This study indicates that trainees also have a number of misconceptions. (C) 2010 Elsevier Ltd. All rights reserved.