Probing high school students’ understanding of interference and diffraction of light using standard wave optics experiments

Demonstration interviews with 27 high school students (18–19 years old) were conducted in Zagreb, Croatia, using several standard experiments on interference and diffraction of light. Students were asked for their predictions, observations, and explanations of the experiments. In this process, many student difficulties were identified, both regarding their understanding of interference and diffraction of light, but also regarding their skills of systematic observation and description of experimental patterns. The observed difficulties were analyzed in the resource-based model, suggesting the activation of some $p$ prims, as well as other cognitive resources in the process of students’ attempts to predict, describe, and explain the interference and diffraction patterns.

Figure 1

Schematic representation of the experimental setup.

Figure 2

Patterns obtained in experiments shown to the students.

Figure 3

Frequencies of students’ predictions for double-slit experiment, with some examples of students’ sketches and comments.

Figure 4

Frequency of students’ predictions for optical grating ($80\text{lines}/\mathrm{mm}$), with some examples of students’ sketches and comments.

Figure 5

Frequencies of students’ predictions for optical grating ($300\text{lines}/\mathrm{mm}$), with some examples of students’ sketches and comments.

Figure 6

Frequencies of students’ predictions for optical grating ($80\text{lines}/\mathrm{mm}$) illuminated with white light, with some examples of students’ sketches and comments.

Figure 7

Frequencies of students’ predictions for a single wide slit, with some examples of students’ sketches and comments.

Figure 8

Frequencies of students’ predictions for the single narrow slit experiment, with some examples of students’ sketches and comments.

Figure 9

Frequencies of students’ explanations of double-slit experiment with some examples of students’ sketches and comments.

Figure 10

Frequencies of students’ explanations of the optical grating experiment with some examples of students’ sketches and comments.

Figure 11

Frequencies of students’ explanations of the single narrow slit experiment with some examples of students’ sketches and comments.