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Unformatted text preview: Ch. 26 HW Solutions 2.) Using the law of reflection we can calculate how tall the mirror must be for the person to see the top of his head and the bottom of his feet. Examination of the figure illustrates that the top two triangles are identical and the bottom two triangles are identical (due to the law of reflection). Since the mirror only spans one of each triangle, the mirror must be at least half the height of the person, or 1 . 7 / 2 = 0 . 85 m. 6.) The sun is very far away so its rays at the mirror will be approximately parallel. Par- allel rays reflect from a sperical mirror through the focal point, which is half the radius of curvature, f = R/ 2 = 3 / 2 = 1 . 5 m. The object should be placed here to receive the most radiation for heating. 11.) With f = 40 cm and given value of p for each part, we calculate the image loca- tion using 1 /p + 1 /q = 1 /f or rewritten q = pf/ ( p- f ) , and we calculate the image height using M =- q/p = h i /h o or h i = h o (- q/p ) . (a) p = 120 cm: q = (120)40 / (120- 40) = 60 cm. The image is real since q > ....
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- Summer '08
- Applied Physics, Angle of Incidence, Snell's Law, Total internal reflection