Test 2 Solutions(07)

Test 2 Solutions(07) - PHYS 212 Second Hour Exam Name March...

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Unformatted text preview: PHYS 212 Second Hour Exam Name March 8, 2007 Problem Session: Hr Instr _ Show all work for full credit! Answers must have correct units and appropriate number of significant digits. .For all the problems (except for multiple choice questions), start with some combination of (a) a fundamental equation (b) a sentence explaining your approach; or (c) a sketch. c=3><108m/s vmd=34o m/s 1. (12 pts) You are playing your slide whistle softly. At a particular slide location, the sound has a frequency 1200 Hz (this is the lowest frequency that it can play at that slide location). Keeping the slide location fixed, you blow harder and the whistle makes a squeaking sound. Assume that the slide whistle is closed at one end and open at the other end. Explain with sketches what has happened and calculate the frequency of that squeaking sound. st’i' {frequency Mbjfi i .1 >:Lo) A: [—{L /—/" 'I/AA: r» Lt ' \ M e ymkear WWW you io/cw [wt/cf) _ x “ -~ .2 _ ‘ oflfilwy em. Ir; (7% a)“ ' 71‘ A “7 77‘ T: )1 -: L ‘% %; 7%Lm 37985? >F:\4N§A 3 Al (:2 Li R _ 2. (9 pts) You are looking at a bright light bulb through a diffraction grating. Assume all other lights are off. Describe carefully what you see, including the relative positions of any colors. \ g Adam furs 149% {57W C) O C: Q gibafi/ WM . I ' mihéb 5 M Maw"? m‘fl 10 A / Wf/agegwsaff j: A55 [65" 5/ r K Y“ .‘ W‘ll WM? 5? [Fm icon/a M003: 3/ {fig/Z) 3. (.15 pts) The electric field in a traveling EM wave is given by" E = (4.0x103 N/C) sin(9.0y + 2.7><1'09 t) 12 where distance is in meters-and time is in seconds. a) .Determine the wavelength oi: wave bio =3? ’7 qt: gm (09“) b) Determine the direction of propagation of this Wave. (Circle one.) 2—5212—12 c) Write down an expression for the magnetic field of this wave. . w - , 6%“? : 4.0m (a: “we r;— 3wo" "/5. I z "I" ohms/rhea {7 RHK . k - a T $49.03 or 4. (13 pts) A square loop of side a = 0.6 m sits in the x-y plane as shown. Throughout the plane of the loop is a uniform magnetic fieldE = (6 — 0.5 t2) [2 , where tis in seconds and E is in Tesla. Determine the emf in the loop at time t = 3 s. d5 . gs : M395" :KA’ Him-r115. .. it}- ‘ 1'2). - 5'2? 6? ,.. jg ; 140m“ -CO.6m) dt(6 0- ) 5. (8 pts) A circular loop of wire is in the plane of the page. The . . . . . upper half of the loop is in a region of uniform magnetic field directed out of the page, while the lower half of the loop is in a region with no magnetic field. For each of the following situations determine whether there is an induced current in the loop at the moment shown and, if so, if the induced current is flowing clockwise or counterclockwise. - - ' - " __ WK ,2? a) Theloo 1 movm toward the to ofthe a e: _ ; 1 '3 as-Ic «a $3 3 q: L ‘ p e % I‘ncho-Qu g SLAqucguij ‘37 ceJ * off ® counter-clockwise no current a? b) The loop is rotating about a vertical axis with the left side moving into the page and theH K right side moving out of éhe [page a, GP Mag-LI _\’ i-MJMQALE Saw .—.» 4) '- Bf’f-ws Eh"- clockwise no current 2? c) The loop is moving to the right: ' 4, M .5 clockwise counter-clockwise :2? d) The loop is rotating clockwise about its center: 4) M g 4 Q) clockwise counter-clockwise 6. (16 pts) Light of wavelength 600 nm passes through a single-slit arrangement and makes a pattern of bright and dark fringes on a distant screen. 99 a) What is the phase difference between the beams coming from the top and bottom edges of the slit corresponding to the second side minimum? (Circle oneLgH ngrob. m‘m‘.mw-'* sin ‘ 1 0 m2 1: 3m 211: SM 311: 71:12 9115/2 5n 111t/2 611: H? b) This second Side minimum is 3a from the central Determine the width of the .,§1it- , we!“ ,. | s , W, 2 3\°l-lmm,% As“, H. g (fir A Eik a; ) “'— 3' i200 km 5‘- 1 A -1 Met: 2w 1'“ _ ‘ /10 Ne» 3" mom l2 21 m‘5 f . (h s __ g __._. :‘ ‘ o .= . . M diSVMScxw—ww Mao: °“ 5 9 a) 0‘ sue $243") Sm?) Turn test over for last 2 problems. AH /SI\’O Al 6L: 7. (12 pts) Two waves are given by y1(x, t) @osfl 0x—25t) and y2(x,t) — os(le-—25t+n/2). Determine the amplitude of the superposition y1 + yz. As always, show all work for full credit. 6 I put; A237 Agtgz’g’:/u\/z Useg phflxSor addition} 71% 51 9% H 8. (15 pts) You are driving on a road directly toward three equally-spaced radio towers (labeled Sl, $2, and S3) as shown in the diagram. The towers broadcast a radio wave with a wavelength 3.5 111. All three towers are broadcasting, and the electromagnetic wave reaching your car from each individual tower has an amplitude A0. However, the total amplitude from all three towers is zero at your car. (a) Draw a phasor diagram corresponding to this situation. so Phasar‘ diajmm musf CLOSE (b) Determine a possible value of the spacing d between the radio towers for this situation. To CloSC/ egailetwal +¢§4«j/e has Agzlzoozflfi‘é A 23S : £3 Then AS: 2%‘AV‘ $0 AV‘; 7‘ 3% (3:513 Qfi-fl Pram d i432 vémd":.[\r, — V11 :EQ»EDD+ 2d) ‘ flavour»; <1 5'0 dznrzi7/ém a [(17% ...
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This note was uploaded on 04/07/2008 for the course PHYS 212 taught by Professor Ladd during the Spring '08 term at Bucknell.

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Test 2 Solutions(07) - PHYS 212 Second Hour Exam Name March...

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