Alternative conceptions concerning interference and diffraction of light

[摘要] The aim of this study was to determine whether alternative conceptionsabout interference and diffraction do indeed exist, to identify the mostimportant of these conceptions and to determine whether theseconceptions relate to textbooks, as one of the main sources of students'knowledge. An analysis of secondary level textbooks and tertiary levelnon-calculus textbooks revealed that presentations of constructive anddestructive interference, diffraction and other related aspects are treatedinconsistently and in some cases contradictorily by different authors. Theresearch instrument was a Physical Optics test which Physics students ofthe Technikon Pretoria wrote. This test revealed that alternativeconceptions on elementary principles of interference and diffraction oflight do exist and that they relate to textbook presentations. This studyreveals that (i) the terms in phese and out of phase are not consistentlyused in different textbooks; (ii) the definitions of constructive anddestructive interference in terms of phases cause major aiternativeconceptions, (iii) the interrelation between interference and diffraction isnot clarified.

[发布机构] University of the Witwatersrand