User's Manual

Beginning Optics System Teacher’s Guide

Experiment 9: Apparent Depth

Typical results:

Typical ray-tracing results are represented at

50% scale in Figure TG.1. The gray regions

represent the actual light beams; the black

lines and dots represent the student’s actual

marks. Notice that this student traced along the

edges of the light beams.

The actual thickness of the rhombus is

t = 3.175 ± 0.025 cm. Based on the accepted

value of n = 1.49, the theoretical apparent

depth is d =2.13.

Answers to questions: 1. Of the two methods, the parallax method is the more precise. Using that method,

both d and t could be measured with a precision of less than 1 mm. Using the ray-tracing method, the points at

which the rays crossed had a larger uncertainty due to the thickness of the light beams. 2. For the typical data

above, the percent differences between the accepted and experimental values of n are 0.7% for Part 1 and 5% for

Part 2.

Experiment 10: Focal Length and Magnification of a Thin Lens

Note on equipment: Provide students with the +100 mm mounted lens. Cover the focal length indicated on

the label. Other converging lenses will work, but you may have to modify the light source-to-screen values given

in Table 10.1.

Part 1: For a distant object, 1/d

approaches zero, therefore the image will form clearly with a lens-to-screen

distance of d

= f ≅ 10 cm.

Table 1.1: Results

dtn

Part 1: Parallax method 2.12 cm 3.18 cm 1.50

Part 2: Ray-tracing method 2.23 cm 3.18 cm 1.43

2.23 cm

Figure TG.1