Comparing different approaches to visualizing light waves: An experimental study on teaching wave optics

Research has shown that students have tremendous difficulties developing a qualitative understanding of wave optics, at all educational levels. In this study, we investigate how three different approaches to visualizing light waves affect students’ understanding of wave optics. In the first, the conventional, approach light waves are represented by sinusoidal curves. The second teaching approach includes representing light waves by a series of static images, showing the oscillating electric field vectors at characteristic, subsequent instants of time. Within the third approach phasors are used for visualizing light waves. A total of $N=85$ secondary school students were randomly assigned to one of the three teaching approaches, each of which lasted a period of four class hours. Students who learned with phasors and students who learned from the series of static images outperformed the students learning according to the conventional approach, i.e., they showed a much better understanding of basic wave optics, as measured by a conceptual survey administered to the students one week after the treatment. Our results suggest that visualizing light waves with phasors or oscillating electric field vectors is a promising approach to developing a deeper understanding of wave optics for students enrolled in conceptual level physics courses.

Figure 1

Keating’s [39] explanation of second minimum occurrence for single-slit diffraction; the length $AC$ represents the path difference of the two waves from the upper and lower edge.

Figure 2

CT approach: Visualizing the processes that underlie the occurrence of maxima and minima in double-slit interference.

Figure 3

SEV approach: Visualizing the processes that underlie the occurrence of maxima in double-slit interference.

Figure 4

$P$ approach: Visualizing the processes that underlie the occurrence of the interference pattern in double-slit interference.

Figure 5

Box plots that describe the distribution of test scores across comparison groups. Theoretically, the test-score scale ranges from 0 to 15 points. Circles represent outliers.