AccelePrep for the ACT Test 2nd Edition Student Text

216 • S URGE TO S UCCESS ! S CIENCE T EST P REP

Experiment 1 A student places an LED candle 100 centimeters from a thin converging lens. A paper screen on the other side of the lens is moved until a sharply focused image of the candle light appears on the screen (Figure 1). The image distance and height are measured. The candle is moved 20 centimeters closer to the lens and the experiment repeated until an object distance of 20 centimeters ‹• ”‡ƒ…Š‡†Ǥ ‘” ‡ƒ…Š †ƒ–ƒ •‡–ǡ –Š‡ ƒ‰‹ϐ‹…ƒ–‹‘ ‹• calculated (Table 1). Table 1 Object Distance, o (cm) Image Distance, i (cm) Image Height, h’ (cm) 0DJQLÀFDWLRQ 100.0 11.1 ȂͲǤͷͷ –0.11 80.0 11.4 –0.71 –0.14 60.0 12.0 –1.00 –0.20 40.0 ͳ͵Ǥ͵ –1.66 ȂͲǤ͵͵ 20.0 20.0 ȂͷǤͲͲ –1.00 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 Object Distance, o (cm) Image Distance, i (cm) Image Height, h’ (cm) 0DJQLÀFDWLRQ 100.0 ͷǤ͵ –0.27 ȂͲǤͲͷ 80.0 ͷǤ͵ ȂͲǤ͵͵ –0.07 60.0 ͷǤͷ –0.46 –0.09 40.0 ͷǤ͹ –0.71 –0.14 20.0 6.7 –1.68 ȂͲǤ͵Ͷ Experiment 3 Using a similarly sized waterproofed LED candle and white plastic screen, the student repeats š’‡”‹‡– ͳ ‹ ƒ ™ƒ–‡”Ǧϐ‹ŽŽ‡† –ƒ —–‹Ž –Š‡ Ž‡‰–Š ‘ˆ –Š‡ –ƒ ’”‡˜‡–• ˆ—”–Š‡” ‡ƒ•—”‡‡–•Ǥ ƒ„Ž‡ ͵ summarizes the results.

Table 3

Object Distance, o (cm)

Image Distance, i (cm)

Image Height, h’ (cm)

0DJQLÀFDWLRQ 100.0 ͸͵Ǥͻ Ȃ͵ǤʹͲ –0.64 80.0 76.1 –4.76 ȂͲǤͻͷ 60.0 88.1 Ȃ͹Ǥ͵Ͷ –1.47 1. According to the experimental results, the ƒ‰‹ϐ‹…ƒ–‹‘ ˆ‘” –Š‡ ’ƒ‹”‡†…‘˜‡”‰‹‰ Ž‡•‡• in air is: 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. 2. Which of the following best describes the ’—”’‘•‡ ‘ˆ š’‡”‹‡– ͵ǫ F. To study how image formation is affected by changing the object used to form the images 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 3. Based on the information provided, approximately how tall are the LED candles used in these experiments? Ǥ ͷ… B. 10 cm C. 20 cm D. Cannot be determined from the given information