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ERIC Number: EJ1033126
Record Type: Journal
Publication Date: 2014-Apr
Pages: 3
Abstractor: As Provided
Reference Count: 5
ISBN: N/A
ISSN: ISSN-0031-921X
The Confirmation of the Inverse Square Law Using Diffraction Gratings
Papacosta, Pangratios; Linscheid, Nathan
Physics Teacher, v52 n4 p243-245 Apr 2014
Understanding the inverse square law, how for example the intensity of light or sound varies with distance, presents conceptual and mathematical challenges. Students know intuitively that intensity decreases with distance. A light source appears dimmer and sound gets fainter as the distance from the source increases. The difficulty is in understanding why the intensity decreases as 1/r [superscript 2] rather than as 1/r or 1/r [superscript 3], or even as 1/ vr, where r is the distance from the source. This paper describes a simple experiment that verifies the inverse square law using a laser pointer, a pair of diffraction gratings, and a ruler. The method examines how the rectangular area outlined by bright spots produced by a laser beam going through a pair of diffraction gratings varies with the distance to the screen. These bright spots are the result of diffraction and interference caused by the diffraction grating assembly. The relationship between the area marked by these bright spots and the diffraction gratings-screen distance is an indirect confirmation of the inverse square law.
American Association of Physics Teachers. One Physics Ellipse, College Park, MD 20740. Tel: 301-209-3300; Fax: 301-209-0845; e-mail: pubs@aapt.org; Web site: http://scitation.aip.org/tpt
Publication Type: Journal Articles; Reports - Descriptive
Education Level: N/A
Audience: N/A
Language: English
Sponsor: N/A
Authoring Institution: N/A