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Unformatted text preview: wilson (kw22588) – HW14 – Mackie – (20224) 1 This printout should have 19 questions. Multiplechoice questions may continue on the next column or page – find all choices before answering. 001 10.0 points A butterfly at eye level is 27 cm in front of a plane mirror. You are behind the butterfly, 78 cm from the mirror. What is the distance between your eye and the image of the butterfly in the mirror? Correct answer: 105 cm. Explanation: The butterfly’s image is 27 cm behind the mirror, so the distance from the image to your eye is 105 cm. 002 10.0 points A concave mirror has a focal length of 35 cm. What is the magnification if the object’s distance is 136 cm? Correct answer: . 346535. Explanation: Basic Concepts: 1 p + 1 q = 1 f = 2 R m = h ′ h = q p Concave Mirror f > ∞ >p> f f <q < ∞ >m>∞ f >p>∞ <q < ∞ >m> 1 Solution: Let q be the image distance and o the object distance. From the mirror equation 1 o + 1 q = 1 f m = q o Combining the two equations yields m = f f o = . 346535 . 003 10.0 points An object is 16 . 3 cm from the surface of a reflective spherical Christmastree ornament 6 . 05 cm in radius. What is the magnification of the image? Correct answer: 0 . 156533. Explanation: 1 p + 1 q = 1 f = 2 R M = h ′ h = q p Convex Mirror > f ∞ >p> f <q < <M < 1 Let : R = 6 . 05 cm , and p = 16 . 3 cm . p is positive since it is in front of the mirror and R is negative since it is behind the mir ror. A spherical Christmastree ornament is a convex mirror, so 1 p + 1 q = 2  R  . We are given the object distance, p and  R  . Inserting these values into the mirror equation and solving for q , we find q = 1 2 R + 1 p = 1 2 (6 . 05 cm) + 1 (16 . 3 cm) = 2 . 55149 cm . The magnification is given by M = q p = 2 . 55149 cm 16 . 3 cm = . 156533 . wilson (kw22588) – HW14 – Mackie – (20224) 2 004 10.0 points A plane convex lens is made of glass (index 1 . 33) with one flat surface and the other hav ing a radius of 40 cm. What is the focal length of the lens? Correct answer: 121 . 212 cm. Explanation: Basic Concepts: 1 f = ( n 1) parenleftbigg 1 R 1 1 R 2 parenrightbigg Solution: From the lens formula 1 f = ( n 1) parenleftbigg 1 R 1 1 R 2 parenrightbigg ⇒ f = R n 1 = (40 cm) (1 . 33) 1 = 121 . 212 cm . 005 (part 1 of 4) 10.0 points An object is placed 10 m before a convex lens with focal length 6 . 1 m . Another convex lens is placed 25 . 7 m behind the first lens with a focal length 3 . 3 m (see the figure below). Note: Make a ray diagram sketch in order to check your numerical answer. 5 10 15 20 25 30 35 40 p 1 f 1 f 1 10 m 6 . 1 m f 1 = f 2 f 2 25 . 7 m 3 . 3 m f 2 = At what distance is the first image from the first lens?...
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 Spring '08
 Turner
 Physics, Correct Answer, Photographic lens

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