Radio Wave Errors: Students Mistaking Radio Transverse Electromagnetic Light Waves as Longitudinal Sound Waves

Commonly anecdotally noted among physics instructors is that students often misidentify radio-waves as sound waves, not as part of the electromagnetic light-energy spectrum. To highlight the prevalence of this error, a pilot survey, whose results are presented here, was made of a total of 225 high school physics students from four high schools in New Jersey in the USA, taken immediately after students had covered both sound and electromagnetic radiation. Note that although the study is made in one locality, there is likelihood that the same data would be obtained in any introductory physics classroom and future studies are suggested. This survey suggests that a majority of students appear to still incorrectly conclude that 'radio waves' are sound, even after instruction otherwise.  This is perhaps reinforced by students' sensory illusion interpretation which might be articulated as: "I hear a radio, I experience 'radio broadcasts' as sound, so if 'radio signals' are 'radio waves', they are hence sound waves". The survey results were also sought to see if students who responded that "radio waves are sound" in this study, more consistently answered other related questions that used that assumption - that is, once they made that decision, did they stick with it, even when not consecutively asked the questions in the survey? Or is it possible that aspects of questioning or syllabi can mislead students? To help teachers assist students in properly identifying radio waves some ideas are suggested, particularly directly challenging students to realize that this is a frequent misunderstanding.