PASCO OS-8459 Beginning Optics System - Manual (Page 47)

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M o d e l N o . O S - 8 4 5 9 T e a c h e r ’ s G u i d e
47
Part 2: Typical results.
y-intercept = 1/f = 0.0977 cm
-1
x-intercept = 1/f = 0.103 cm
-1
Answers to questions: 1. The image if inverted. 2. The image is real because it can be viewed on a screen.
3. For a given object-to-image distance, the two object distance-image distance pairs are the inverse of each
other, which demonstrates the reversibility of light through a lens. 4. The magnification is negative because the
image is inverted. 5. The three determined values of f are unlikely to be exactly equal, primarily due to measure-
ment error.
Table 10.1: Image and Object Distances
Distance from
light source to
screen
d
o
(cm)
d
i
(cm)
1/d
o
(cm -1 )
1/d
i
(cm -1 ) Image Size Object Size
100 cm
88.5 11.5 0.0113 0.0870 5.5 mm 42 mm
11.0 89.0 0.0909 0.0112 81 mm 10 mm
90 cm
78.3 11.7 0.0128 0.0855
11.3 78.7 0.0885 0.0127
80 cm
68.0 12.0 0.0147 0.0833
11.5 68.5 0.0870 0.0146
70 cm
57.7 12.3 0.0173 0.0813
11.9 58.1 0.0840 0.0172
60 cm
47.1 12.9 0.0212 0.0775
12.3 47.7 0.0813 0.0210
50 cm
36.0 14.0 0.0278 0.0714
13.4 36.6 0.0746 0.0273
Table 10.2: Focal Length
f
Result from x-intercept 9.75 cm
Result from y-intercept 10.2 cm
% difference between results from intercepts 4.4%
Average of results from intercepts 9.98 cm
Result from Part I 10.0 cm
% difference between Average of results from intercepts and result from Part I 0.2%
Table 10.3: Magnification
Point 1 Point 2
calculated from image and object distances -0.130 -8.09
calculated from image and object sizes 0.13 8.1
% difference 0% 0.1%
M
M