This study describes the possible variations of thought experiments in terms of their nature, purpose, and reasoning resources adopted during the solution of conceptual physics problems. A phenomenographic research approach was adopted for this study. Three groups of participants with varying levels of physics knowledge-low, medium, and high level-were selected in order to capture potential variations. Five participants were selected within each level group and the study was conducted with fifteen participants in total. Think aloud and retrospective questioning strategies were used throughout the individually conducted problem solving sessions to capture variations in the participants' thinking processes. The analysis of the data showed tha...