Physics 202 Homework, Day 23: Chapter 23: #21,29,31,33,38,41;
ü 21. A cubical block of ice 50.0 cm on an edge is placed on a level floor over a speck of dust. Locate the
image of the speck, when viewed directly from above, if the index of refraction of the ice is 1.309.
ü 29. A contact lens is made of plastic with an index of refraction of 1.50. The lens has an outer radius of
curvature of +2.00 cm and an inner radius of curvature of +2.50 cm. What is the focal length of the lens?
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ü 31. A converging lens has a focal length of 10.0 cm. Locate the images for object distances of (a) 20.0 cm,
(b) 10.0 cm, and (c) 5.00 cm, if they exist. For each case, state whether the image is real or virtual, upright
or inverted, and find the magnification.
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ü 33. A diverging lens has a focal length of 20.0 cm. Locate the images for object distances of (a) 40 cm, (b)
20.0 cm, and (c) 10 cm. For each case, state whether the image is real or virtual, upright or inverted, and
find the magnification.
ü 38. A convex lens of focal length 18.0 cm is used as a magnifying glass. At what distance from a tiny
insect should you hold thi slens to get a magnification of +3.00 ?
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ü 41. Two converging lenses, each of focal length 15.0 cm are placed 40.0 cm apart, and an object is placed
30.0 cm in front of the first lens. Where is the final image formed, and what is the magnification of the
system?