This study aims to develop a multiple-choice instrument for determining students’ concepts about the
photoelectric effect. To develop the instrument, 30 students taking the Modern Physics course were
interviewed to determine their misconceptions about the photoelectric effect. These misconceptions
were compared with the misconceptions set out in the literature so that a decision could be made to
define the questions and distractors to be used in the instrument. The content validity of the
inventory was achieved on the basis of the feedback received from ten experts. The inventory was
administered to 295 students enrolled in the Physics Teaching and Science Teaching Departments and
discrimination index, difficulty index, and point biserial coefficient values were determined for
each item. Cronbach’s alpha coefficient was calculated for the whole of the test. The results of the
analysis reveal that the inventory is both valid and reliable.