Victory for the ACT Student Text 15e

318 • S CIENCE

Experiment 2 The student repeats Experiment 1 after replacing the single lens with two identical lenses side-by-side and in contact with each other. Table 2 summarizes the results.

Table 2 Figure 1

Object Distance, o (cm)

Image Distance, i (cm)

Image Height, h’ (cm)

100.0 80.0 60.0 40.0 20.0

5.3 5.3 5.5 5.7 6.7

–0.27 –0.33 –0.46 –0.71 –1.68

–0.05 –0.07 –0.09 –0.14 –0.34

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Experiment 3 Using a similarly sized waterproofed LED candle and white plastic screen, the student ”‡’‡ƒ–• š’‡”‹‡– ͳ ‹ ƒ ™ƒ–‡”Ǧϐ‹ŽŽ‡† –ƒ —–‹Ž –Š‡ Ž‡‰–Š ‘ˆ –Š‡ –ƒ ’”‡˜‡–• ˆ—”–Š‡” measurements. Table 3 summarizes the results. Table 3 Object Distance, o (cm) Image Distance, i (cm) Image Height, h’ (cm) 0DJQLÀFDWLRQ 100.0 63.9 –3.20 –0.64 80.0 76.1 –4.76 –0.95 60.0 88.1 –7.34 –1.47

Use POE Notice that each of the answer choices for item #30 mentions a different independent variable. Use the process of elimination to identify the independent variable in Experiment 3 and rule out the wrong answers.

Which of the following best describes the purpose of Experiment 3? F. To study how focal length is affected by changing the medium surrounding a pair of converging lenses G. To study how image formation is affected by combining converging lenses H. To study how image formation is affected by changing the medium surrounding a converging lens J. To study how image formation is affected by changing the position of an object relative to a converging lens

According to the experimental results, for the same object distance, the paired converging lenses in air produces a ƒ‰‹ϐ‹…ƒ–‹‘ǣ A. less than that of a single converging lens in air. B. greater than that of a single converging lens in air. C. equal to that of a single converging lens in air. D. greater than that of a single converging lens in water.

30.

31.