54S09Exam2Solution

# 54S09Exam2Solution - Patt l ghott antswet(4pm each Circle...

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Unformatted text preview: Patt l: ghott antswet (4pm each) Circle the best armver: 1) . lﬂvx all, . L“, n r. _ ,.‘~v ._ i Staci bat magnet moons es a magnate lieict With a a—con’inonen‘t l5; ~ l clos: to HS l‘l ole, “which the leit the cubical sl‘io’w‘v‘a~ At the 'itgl‘t 3: ‘ 1. {it} must be positive, and the magnetic ﬁeld; must curve outward from the z-axis. . b) must be negative, and the magnetic ﬁeld must curve outward from the z-axis. c) must be positive, and the magnetic field must be parallel to the z—axis. d) must be negative, and; the magnetic field must parallel to the z—axis. am: :3 5120?? Qg‘féf‘ﬁQWﬁ/tﬁ eemseifagﬁi go Jete‘eege Mfg??? ﬁfetjeegg alt Weed Q egg ' ’ ‘3: «Z a? leg /e§% cal/Vt?" F Viogeas-%=' 2) A loop is moving to the right in the magnetic ﬁeld of a wire as shown. T he induced current in the loop ﬂows g; clockwise and the net magnetic force on the loop is to the right. w clockwise and net magneticfotce on the loop is to the left. c) counterclockwise and net magnetic force on the loop is to the right. d) counterclockwise and net magnetic force on the loop is to the left. exam *@ I? a I" g g ,, M? feww l, g .5‘. m e- e 3%? it” ii e A resistor R = 2 Q is connected to the secondary of a transformer ancl an instantaneous cement l = ill A is ﬂotrting through it. if the secondi coil has 10 turns, what is the instehtaneous late of change otﬂwc Webets/sec through one turn of the secondary coil, assmting each is identical? W°\ LN w, i a 0 y 4:; L») i\) 1—4 f? \axv ‘ r‘w «:3 on we @ ﬁgﬁwgygstig @@a{,: Kg f 52-) A plane electromagnetic wave has an electric field in the positive x—direction (up) and a magnetic ﬁeld in the positive y-ditection (out of the page). A hydrogen atom is placed in the laser beam. The electric and magnetic ﬁelds are uniform over the size of the atom and exert forces on the proton (charge +1.6 X 10'19 C) and on the electron (charge —l.6 X 1049 C). At the time shown? The net electn'c force on the atom is zero, while the magnetic force on the atom is along the +2 direction. The net electn'c force on the atom is zero, While the magnetic force is along the —z direction. c) The net force on the atom arising from both the electric ﬁeld and magnetic ﬁelds is zero. , d) The net .nagnetic force on the atom is zero, while the electric force is along is in the -x direction. e) The net magnetic force on the atom is zero, While the electric force is along is in the +X direction. g ; I W «4“ a —. ’ i by «5 f fﬁ rrﬂ i e em A 1 W mpalarized i pelarizer has its cans: first? Where cese = h—A CFC? ht beam is mciciem on We peiai‘izers. The secenci .issien axis crieiited at an angle 8 with respect to the / 3. The power transmitted through the second: peiaﬁzer is ,....\ :3 a) 1/3 W. b) 2/6 W c} 3/9 W. iwﬁg/agg @9 gig? ﬁle; «ﬁéﬁff ﬁg? egg)?” “£225” 5 {Keg 6) Light is incident onto a water film (:1 = 1.33) that is on a piece of glass (11 = 1.5). The thickness t of the water coating is very small compared to the wavelength A of “the light. The reﬂected intensity is close to the minimum. is close to the maximum. cannot be determined. d) decreases with increasing wavelength. 7 Two slits are illttmihatecl with light of wavelength A as shovm. The second minimum the intensity is observed at the point P on the screen 8, counting upward from the center (dotted line). At this point, the path lengths differ by a; y w a E a M W s“ mi Q; :r g W“ Two equal amplitude infrared sources (a) and (b) radiate light in all directions and are separated by a nonzero distance as shown. The wavelength of the light is 7L == 1 pm and the polarization is perpendicular to the page. I observe zero intensity at the point P2 located at equal distance from both sources. I also observe zero intensity at the point P1. The minimum distance between the sources is 1.5 gm. d) 2 pm regative charge 01 = -3 C moves with a velocity V = 5 in/s in at 2T magnetic ﬁeld. i t e a) is 0. h) is out of the 10) A capacitor C with circular plates is initially charged. It is then discharged by connecting it to wires forming a square, causing a current I to ﬂow. At a point P centered with respect to both the capacitor plates and the wires as shown, the net magnetic ﬁeld is a) the same as that of the right hand wire alone. b) twice as large as that of the right hand wire alone. w three times as large as that of the right hand wire alone. four times as large as that of the right hand wire alone . aw) 7“ u 1 a l 5! I I a x F , l y a | 3 m z a ‘ X _ )H , l t l) {25 pts) Two long wires each carry a current l = 20 A. The wires are symmetrically located at distances of d = 5 cm from the origin (X = O). A loop of length L = 5 cm and Width W = 4 cm is being moved in the plane of the page. At the time shown, the loop is located at the center of the two long Wires and cantes a entrent L = 5 X l0'6/s. Use no = 4n l0'7. the net three on the loot) to the two long assumin- enttent l1 flows r1 the dltections shown. b) When the center of the loop lies at X = 0, What is the total ﬂux of the magnetic ﬁeld through the loop clue to the long Wires? (No integrals allowedl). Justify your answer. c) lf the current flows in the loop as shovm, which way is the loop moving? Up, down, right, or left? Justify your answer using Lenz’s Law. cl) lf the moving loop has a resistance of 2 Q, What is the rate of change of ﬂux in Webers/s through it when it is in the position shown? W3, v.1» ' r: W w a» if», A” g f» /» 4 my?“ 5%, MW 49".? 3% ,x km ; w V ; - g’ A Mm . w I m f a? W21" / V W if V; (WA W Am“ My ﬂ? m 3” M 0m" fig 1?“ w 52\$. j W @éﬁ W w ﬂﬁﬁfﬁ} w my 49%, {ﬁg/Lea}? f“??? 5 wwﬂ% “ﬂaw @ﬁ/LT? “Q, y W 565‘” @ ‘5‘ @fg9§/%ﬁ Fwé’fé’mf‘j M3 , ~ ” X/ f a V V} w a. ‘ w, «ft ” " A f: 53 “7 w» “33 Wﬂgg‘é z; J; W «m. ms 5 £3 m if mi“ m "£02k M “a .é' “"2 " if M a” ' 1 WWW / M) J f7?“ 2? 6:33 es? 93%; r ’ w. is J W‘ I m 0%“. n M f? 2 mm W 4:45 a» WW~ w “W” ~ . w W 2/3?— 3 “’ ‘53 i " a"? “j Farréw/é‘ﬂ §§w€q% Ea; gig % /@.§;4; “a Q é [:3 ﬁféwﬁ? w as #32373» mjmg¢ ﬁg:- % {<5} jg? fwm wax xi M 4;”, 7/” fa m a. ‘ gm {5; éfZﬁ/E/%W «W? [email protected]}éL 5% my 6% M Cg” {/ng - ~ «« ‘~—~« W. v~ r I, if ,5 a a? fa /‘“‘”\ \zy/ 2) (20 pts) 3} A large metal sheet (several meters across) carries a current ﬂowing 02a" the page. in the small dotted region of a length 1L (a few em)D Ehe current is E. b) The eater sheefzs each carry an eefwaréi current per unit Eengﬂl 0f 10m /L = 2 Adm, While the central sheet carries an inward eurrent per unit length of En /L = 3 Ajm. Use L10 = wt X 10'7. Give the directions of 3 below the ement sheet in Fig. (a). Ampere’s law to ﬁnd he magnitude 0f magneﬁc ﬁeld in iemzs 0f ’ u per zmz’z‘ 3/1 in. A/m. First draw en dotted. 300p £0 gemg areum- ii. Explain wig-,1 een‘iﬁbuiiens m iniegmi item ﬂee ﬁeﬁ and r1 gh‘i sides vanish b) Use the superpositien principle to ﬁnd the net magnetic ﬁeld at points A and B in Fig. (b). How do the ﬁeids afﬁne shee’is add and subiract in each region? 3) (15pm) Light with e weveleng‘n‘h 0f 9» = 1.53pm hits a thin wedge tiﬁemess exaggeraied for clarify) that is in een‘zae’: with a ﬂat glass plefLe. For the wedge, :11 = 1.5 for the glass plate, :12 = 2.0. a) A bright fringe is Observed in the reﬂecied ﬁght near ~Ehe edge (a), which has a thielmess that is small eempared m 1.5 gm. Explain Why a bright ﬂinge is ObSél’V/‘Sd, in terms of the phase shifts fer the light reﬂected ﬁom each surface 01’? the wedge. 13‘- ‘ "*3 the edge (70)., inelxyeﬁeg‘ 9) Suppose that the glass plate is repieced by a material Wiih 112 = 1.3. For the same wedge thickness t, how do the ﬁinges in the reﬂected light change? a ...
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## This note was uploaded on 05/13/2010 for the course PHYSICS 54L taught by Professor Thomas during the Spring '09 term at Duke.

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54S09Exam2Solution - Patt l ghott antswet(4pm each Circle...

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