This study aimed to investigate the models that co-existed in students' cognitive structure to explain the interactions between electric charges and uniform magnetic fields. The sample consisted of 129 first-year civil engineering, geology and geophysics students from a large state university in western Turkey. The students answered five diagnostic questions, testing their understanding of the interactions between electric charges and magnetic fields. For each question, the students had 100 points to divide between the options in order to indicate the ones that were attractive to them. The study found that many students possessed more than one model competing to explain the phenomenon in each question and they found these models plausible. This study provided further evidence that students' reasoning was context-dependent. However, employing teaching approaches like the learning cycle during the instruction might help students to grasp a more coherent understanding of the interactions between electric charges and magnetic fields. Encouraging students to use metacognitive strategies in science courses might help them to develop the habit of thinking about their thought. This, in turn, might reduce the adverse effects of the cues presented in questions on their reasoning. (Contains 2 tables.)