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ERIC Number: EJ876082
Record Type: Journal
Publication Date: 2010-Jan
Pages: 2
Abstractor: As Provided
ISBN: N/A
ISSN: ISSN-0031-921X
Eyeglasses in the Classroom
Huang, Ding-wei; Huang, Wei-neng; Tseng, Hsiang-chi
Physics Teacher, v48 n1 p12-13 Jan 2010
Optical phenomena can be divided into two categories: ray optics and wave optics. The former is also known as "geometrical optics", and examples are reflection and refraction, while the latter is also known as "physical optics" and includes interference and diffraction. In most textbooks, these two topics are presented in separate chapters. To help students grasp corresponding principles, instructors often emphasize the contrast between these two categories. For example, the length scale of objects encountered by light beams is taken as an indicator to differentiate these two. When the scale is microscopic (down to the wavelength at 550 nm for green light), the light shall be treated as a wave, while at a macroscopic scale (start from a few mm for a tiny lens), the light shall be taken as a ray. Diffraction effects are almost always negligible in the formation of images by lens, and refraction effects can also be neglected safely in the discussions of interference. As a result, some students get the wrong impression that these two phenomena must manifest in quite different regimes. In this paper, we show that eyeglasses can be a very handy tool to demonstrate these two phenomena at the same time, working as a lens for light rays and also showing interference of light waves from reflections off the lens coating. According to a recent survey, more than 80% of college students in Taiwan are nearsighted, and eyeglasses are easily accessible in the classroom. Students are guided to observe, describe, and then provide qualitative explanations. And some of the students might take the challenge to work out quantitative calculations as exercises after class.
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: Higher Education
Audience: N/A
Language: English