<![CDATA[The hydrogen atom spectrum is a fundamental topic in quantum physics education that demands deep conceptual understanding. This study aims to evaluate the conceptual understanding of prospective physics teachers and to map the profile of technology-mediated conceptual reasoning within the operationally delimited bounds of a deliberately restricted Technological Pedagogical Content Knowledge (TPACK) framework. The construct actually measured is technology-mediated conceptual representation and identification, the capacity to interpret and reason about physics concepts when instantiated through digital representation formats or simulations rather than the TPACK construct in its entirety. The study employed a descriptive quantitative case study design (without a qualitative strand) using total sampling across an entire third-year cohort (N = 32) at a state Islamic teacher training institution. Data were collected through a structured 20-item multiple-choice instrument covering Content Knowledge (CK), Technological Content Knowledge (TCK), and technology-mediated conceptual reasoning (labelled TPACK under the limited operationalisation adopted in this study). Responses were analysed using dichotomous Rasch modelling via Winsteps software to convert raw scores into linear logit intervals. Psychometric findings revealed a pronounced ceiling effect, with 34.4% of participants achieving perfect scores and an aggregate mean of 85%; low person reliability (0.56); and two items (14 and 20) yielding extreme measures that could not be estimated. The item difficulty hierarchy indicated that high aggregate performance masked a fragile conceptual architecture: a two-step procedural calculation item (Item 11, p = 0.633, ? = 0.13, SE = 0.38) was the most difficult item, whereas a fundamental item investigating the causal principle of radiation emission (Item 1, p = 0.733, ? = -0.38, SE = 0.41) ranked surprisingly high in difficulty. The domain radar chart displayed a near-equilateral configuration representing an artefact of the ceiling effect and low person reliability rather than a substantive profile. The study concludes that procedural fluency does not guarantee conceptual mastery.]]>
