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# quiz4 - Daniels Matthew Quiz 4 Due Dec 7 2006 midnight Inst...

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Daniels, Matthew – Quiz 4 – Due: Dec 7 2006, midnight – Inst: Ditmire 1 This print-out should have 23 questions. Multiple-choice questions may continue on the next column or page – find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points What is the frequency of an electromagnetic wave if it has a wavelength of 1.2 km? The speed of light is 3 × 10 8 m / s. Correct answer: 250000 Hz. Explanation: Let : λ = 1 . 2 km and c = 3 . 00 × 10 8 m / s . The speed is c = f = c λ = 3 × 10 8 m / s 1 . 2 km · 1 km 10 3 m = 250000 Hz . keywords: 002 (part 1 of 2) 10 points The second-order bright fringe ( m = 2) is 4 . 45 cm from the center line. 4 . 45 cm 1 . 11 m 0 . 0307 mm S 1 S 2 θ viewing screen Determine the wavelength of the light. Correct answer: 615 . 383 nm. Explanation: Let : y = 4 . 45 cm , L = 1 . 11 m , and d = 0 . 0307 mm , r 2 r 1 y L d S 1 S 2 θ = tan - 1 y L · viewing screen δ d sin θ r 2 - r 1 P O 6 S 2 Q S 1 90 Q r 2 r 1 d S 1 S 2 θ = tan - 1 y L · θ δ d sin θ r 2 - r 1 6 S 2 Q S 1 90 Q For constructive interference y bright = λ L d m , (1) with m = 2, y 2 = 0 . 0445 m, L = 1 . 11 m, and d = 3 . 07 × 10 - 5 m λ = d y 2 m L = (3 . 07 × 10 - 5 m) (0 . 0445 m) (2) (1 . 11 m) = 6 . 15383 × 10 - 7 m = 615 . 383 nm . 003 (part 2 of 2) 10 points Calculate the distance between adjacent bright fringes. Correct answer: 2 . 225 cm. Explanation: From equation (1) and the results of the first part of the problem, we get y m +1 - y m = λ L ( m + 1) d - λ L m d = λ L d

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Daniels, Matthew – Quiz 4 – Due: Dec 7 2006, midnight – Inst: Ditmire 2 = (6 . 15383 × 10 - 7 m) (1 . 11 m) (3 . 07 × 10 - 5 m) = 0 . 02225 m = 2 . 225 cm . keywords: 004 (part 1 of 1) 10 points The reflecting surfaces of two intersecting flat mirrors are at an angle of 64 , as shown in the figure. A light ray strikes the horizon- tal mirror, reflects off the horizontal mirror, impinges on the raised mirror, reflects off the raised mirror, and proceeds in the right-hand direction. 64 φ Figure is not drawn to scale. Calculate the angle φ . Correct answer: 52 . Explanation: Basic Concept: θ incident = θ reflected Solution: θ 1 θ 2 φ θ Figure is to scale. The sum of the angles in a triangle is 180 . In the triangle on the left we have angles θ , 180 - θ 1 2 , and 180 - θ 2 2 , so 180 = θ + 180 - θ 1 2 + 180 - θ 2 2 , or θ 1 + θ 2 = 2 θ . (1) In the triangle on the right we have angles θ 1 , θ 2 , and φ . 180 = θ 1 + θ 2 + φ , so θ 1 + θ 2 = 180 - φ . (2) Combining Eq. 1 and 2, we have φ = 180 - 2 θ = 180 - 2 (64 ) = 52 . As a matter of interest, in the upper-half of the figure the angles (clockwise) in the triangles from left to right are 47 , 47 , and 86 ; 94 , 26 , and 60 ; 120 , 17 , and 43 ; 137 , 17 , and 26 ; and in the lower-half of the figure the angles (counter-clockwise) in the triangles from left to right are 17 , 17 , and 146 ; 34 , 26 , and 120 ; 60 , 47 , and 73 ; 107 , 47 , and 26 . keywords: 005 (part 1 of 1) 10 points An object 8 . 6 cm high is placed 7 . 9 cm in front of a convex mirror with a focal length of - 18 cm.
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quiz4 - Daniels Matthew Quiz 4 Due Dec 7 2006 midnight Inst...

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