When introducing the optics of mirrors, an obvious place to start is comparing the appearance of objects to their images. Image distance and magnification are usually covered the most thoroughly, but the handedness of images in various shapes of mirrors has also been discussed in The Physics Teacher1–5 and elsewhere.6 However, there has not been a systematic treatment of handedness. We describe a general criterion in terms of axis inversions for whether or not handedness is preserved by a mirror. We consider how the rotation of mirrors affects the orientation of their images. We also make some suggestions for introducing these topics in introductory courses.
REFERENCES
1.
W.
Thumm
, “A question of mirror reflections
,” Phys. Teach.
10
, 346
(Sept. 1972
).2.
K. W.
Ford
, “Why is your image in a plane mirror inverted left-to-right but not top-to-bottom?
” Phys. Teach.
13
, 228
–229
(April 1975
).3.
I.
Galili
, F.
Goldberg
, and S.
Bendall
, “Some reflections on plane mirrors and images
,” Phys. Teach.
29
, 471
–477
(Oct. 1991
).4.
T. H.
Ansbacher
, “The nonreversing mirror with a twist
,” Phys. Teach.
25
, 104
–105
(Feb. 1987
).5.
P.
Chagnon
, “Animated displays II: Multiple reflections
,” Phys. Teach.
30
, 488
–494
(Nov. 1992
).6.
Paul Doherty, Don Rathjen, and The Exploratorium Teacher Institute, The Magic Wand and Other Experiments on Light and Color (Wiley, New York, 1995), pp. 25–29 and 35–40.
7.
This approach is similar to the virtual mirror method. See for example:
T. B.
Greenslade
Jr., “Multiple images in plane mirrors
,” Phys. Teach.
20
, 29
–33
(Jan. 1982
).8.
The photographs were taken using a “True Mirror” (#MIR-300) from Educational Innovations, Inc., 362 Main Ave., Norwalk, CT 06851, 888-912-7474; http://www.teachersource.com. This double mirror is constructed with front-surface mirrors, so the seam is almost invisible.
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© 2004 American Association of Physics Teachers.
2004
American Association of Physics Teachers
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