Using this link https://phet.colorado.edu/sims/geometric-optics/geometric-optics
ID: 3309158 • Letter: U
Question
Using this link https://phet.colorado.edu/sims/geometric-optics/geometric-optics_en.html
The “No Rays” button is selected, and the pencil is moved above the principal axis of the lens such that its eraser is positioned on the principal axis. Also the pencil is more than twice the focal distance from the lens. Make sure that “curvature radius” is set to 0.8 m, the “refractive index” is 1.5 and the “diameter” of the lens is 1.3 m. Also select the “Virtual Image” and “Ruler” button and make sure a ruler shows up in your window. 20. Position the pencil at 90 cm from the lens (close to the focal length).
Change all the setting back to what you had at the beginning of the lab. Make sure that “curvature radius” is set to 0.8 m, the “refractive index” is 1.5 and the “diameter” of the lens is 1.3 m. Position the pencil at 180 cm from the lens.
25. Change the diameter of the lens from 1.3 m to 0.8 m. How does the image formed through the bigger lens change when the diameter of the lens gets smaller? (1 point)
A. The image becomes bigger.
B. The image becomes smaller.
C. The image does not change.
26. Set the diameter back to 1.3 m. Increase the refractive index to its highest value. What happens to the image formed through the lens? (1 point)
A. The image becomes bigger.
B. The image becomes smaller.
C. The image does not change.
27. Set the index of refraction back to 1.5. Increase the radius of curvature to its highest value. What happens to the image formed through the lens? (1 point)
A. The image becomes bigger.
B. The image becomes smaller.
C. The image does not change.
28. Lenses are used in making magnifying glasses. Which one of the following statements is true concerning a magnifying glass? (2 points)
A. It produces an inverted image.
B. It is made from a diverging lens.
C. It produces a virtual image.
D. The image distance will be less than the object distance.
E. The object must be placed outside the focal point of the lens.
29. The compound microscope discussed in your textbook is made from two lenses. Which one of the following statements is true concerning the operation of this microscope? (2 points)
A. Both lenses form real images.
B. Both lenses form virtual images.
C. Only the lens closest to the eye forms an image.
D. The lens closest to the object forms a real image; the other lens forms a virtual image.
E. The lens closest to the object forms a virtual image; the other lens forms a real image.
30. In a scene from a movie, a nearsighted character removes his eyeglasses and uses them to focus the nearly parallel rays of the sun to start a fire. What is physically wrong with this scene? (2 points)
A. The eyeglasses have diverging lenses and cannot be used to focus parallel rays.
B. The eyeglasses have converging lenses and cannot be used to focus parallel rays.
C. Sunlight cannot be used to start a fire.
D. A fire can only be started if the image is virtual.
E. Parallel rays cannot be focused.
Explanation / Answer
1) The magnification depends on the image distance and object distance rather than the size of the lens. So the image is unchanged.
2) The image size is independent of focal length so the image appears same as long as object and image distances are kept same.
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