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Science · Drill 21

Science practice 21

10 questions ~9 min recommended
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I appreciate you providing this content, but I need to point out an issue: the passage you've shared is a data table (a lens properties reference chart), not a continuous text passage with underlined phrases and embedded question markers. The instructions I follow are designed for **ACT English passages** — prose text with specific words or phrases underlined and marked with question numbers that need to be converted to HTML format. What you've provided appears to be a **science passage (likely ACT Science)** with associated multiple-choice questions, but: 1. There are no underlined phrases in the passage itself 2. There are no embedded standalone digits indicating where questions apply 3. The passage is a structured table, not flowing text **To help you correctly, I would need:** - The original passage text in paragraph form (not a table) - Clear indication of which phrases are underlined (either marked with numbers or described) - OR the original OCR'd text exactly as it appeared, with standalone digits showing where question-markers were printed Could you provide the passage in that format, or clarify if you meant to submit a different passage?

Lenses are made of transparent materials such as glass and plastic and are used in eyeglasses, cameras, and telescopes, as well as other applications. When light rays enter a curved lens from a distant object, the rays are bent into new angles. A convex lens, which is thicker in the middle, takes parallel light rays and converges them toward a common point called the focal point. The focal length is defined as the distance from the center of the lens to the point where the bent rays converge. A concave lens, on the other hand, is thinner in the middle and diverges parallel light rays as if they came from a point ahead of the lens (this point is one focal length from the lens). Both lenses are shown in Figure 7.1.

Figure 7.1

In conventional ray diagrams, the source of light (the object) is to the left of the lens and the rays move to the right through the lens. Light rays leave objects at various angles and are bent by the lens to form an image of the distant object. Real images are formed when actual light rays converge to a common point to the right of the lens. Virtual images are formed when the observer looks backward through the lens and sees an image on the same side of the lens as the object. Table 7.1 summarizes the images observed by these lenses.

TABLE 7.1

1. When the human eye views distant objects, the light rays go through a lens that is thicker in the middle. An image forms on the retina, which is the inner back surface of the eye. Which of the following best identifies the eye's lens and the characteristics of the image?

2. According to the information provided in the passage and Table 7.1, which of the following statements is true?

3. A particular convex lens in a camera has a focal length of 10 cm. If the object for the picture is 30 cm from the lens, what type of image will form on the film?

4. Rays of light from the distant sun reach the earth nearly parallel with each other. A child wishes to take these rays of light and use them to burn a piece of paper. What type of lens should the child use, and how far from the center of the lens should the paper be?

5. A slide projector uses a convex lens with a focal length of 120 mm. A small picture on a transparent slide is placed upside down in the projector, 125 mm in front of the lens. What will the image on the screen look like?

6. Eyeglass lenses may be used to correct both nearsighted and farsighted vision. Someone who is farsighted has difficulty seeing tiny objects that are close to the lens. As farsighted patients look through corrective lenses toward the object, they are able to see a larger image clearly on the same side of the lens as the object. What type of lens corrects farsighted vision, and what is the orientation of the image to that of the object?

7. A copy machine has a lens with a focal length of 30 cm. How far from the lens must a document (the object) be placed if the copy (the image) is to be exactly the same size?

8. A child looks through a lens at the distant trees, and the trees still look distant but appear smaller. What type of lens is the child looking through, and is the image upright or inverted?

9. A 15-cm focal-length lens is used to focus a sharp image on a piece of paper that is 20 cm to the right of the lens. What information is known about the lens and the object?

10. In Figure 7.2, Point "F" represents the focal point of the lens. If the candle is placed as shown in the figure, what type of image will be seen?


Figure 7.2

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