HW6%20solutions

HW6%20solutions - For film surrounded by lower index media...

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Hw6 Physics 204, Summer 2008 Weihua Zheng Part 1 2,3 omitted. 4. Without the glasses, the farsighted person can only see the newspaper by holding it 48cm away from his eyes . With the glasses, he can hold the newspaper 25 cm away from and read. So he wants to put up convex lens (glasses) x cm away from his eyes, so that for the convex lens, d O =25-x (cm), d i =-(48-x) (cm), negative signs means it s a virtual image, the image is on the same side of the lens with the object. a. x=2 cm, cm d d d d f o i o i 46 23 46 23 46 = + × = + = x d O d i glasses newspaper b. x=3 cm, cm d d d d f o i o i 43 22 45 22 45 = + × = + = 5. Omitted 6. To get the angle for DARK fringe: θλ sin ) 2 1 ( d m = + , To get the angle for BRIGHT fringe: θ λ sin d m = , where m=0,1,2,3 a.Dark, m=0: o 8 . 3 sin 10 8 . 3 10 505 2 1 6 9 = × = × × θθ b.Bright, m=1: o 6 . 7 sin 10 8 . 3 10 505 1 6 9 = × = × × c.Dark, m=1: o 5 . 11 sin 10 8 . 3 10 505 2 3 6 9 = × = × × d. Bright, m=2: o 4 . 15 sin 10 8 . 3 10 505 2 6 9 = × = × × Dark, m=0 Dark, m=1 Bright, m=1 Bright, m=2

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7. d D m y D y d d m λ θλ = = = sin , m d D m y y 3 3 9 1 2 1 2 10 6 . 3 10 171 . 0 05 . 2 10 ) 565 665 ( 3 ) ( × = × × = = λλ Part 2 8.To make the film look red, we need the green light destructed by the interference.
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Unformatted text preview: For film surrounded by lower index media and destructive interference, we have nm t t nt m 2 . 198 39 . 1 2 551 1 2 = ⇒ × × = × ⇒ = . Note that larger m value results in thicker film. 9. For film surrounded by lower index media and constructive interference, we have n m t nt m 2 ) 2 1 ( 2 ) 2 1 ( + = ⇒ = + For m=1, nm t 9 . 342 33 . 1 2 608 2 3 = × × = For m=2, nm t 4 . 571 33 . 1 2 608 2 5 = × × = 10. a. s t t c v t t 9 2 8 2 2 10 8 . 3 992 . 1 10 3 1 ' − − × = Δ ⇒ − Δ = × ⇒ − Δ = Δ b. m t v L 13 . 1 10 8 . 3 10 3 992 . ' 9 8 = × × × × = Δ = − 11. s s s c v t t c v t t 4 2 8 2 2 2 2 2 10 4 1209600 ) ) 10 3 ( 7790 2 1 ( ) 3600 24 14 ( ) 1 1 ( ' 1 ' − × = × × × ≈ × × × − − = Δ − Δ ⇒ − Δ = Δ...
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HW6%20solutions - For film surrounded by lower index media...

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