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Unformatted text preview: Multiple Choice Questions
Enter solutions in the table on the front of your exam booklet. l. The SI unit of current is A] Farad
B] Henry
C] Tesla
D] Coulomb (: __<E;]X;Ampere
2. In which of these situations will there be a nonzero displacement current? capacitor is being charged. g .1: . t
" B] The current through a solenoid is varied. ' ' 7 ‘
C] A light bulb is turned on. D] A magnet is dropped into a metal pipe.
E] None of the above. 3. A uniform magnetic ﬁeld of magnitude 2T is oriented in the +2 diregtipmn. An electron ._ _ _ . enters this region of magnetic ﬁeld with oo“t“”"nitia1 velocity of10Vin/sin”therJEMdirectiom It
will feel a force of  ~ — ‘_ ‘w.,_.. y _n__ ....... ..rc_ _._w ...,_‘_ “:2 _ .7; é) A] 3.2 x 10'19 N in the +y direction if “ "v" ’3 iv L"
B] 3.2 x 10'“) N in the —y direction " M, ‘ H .
. C] 3.2 x 10‘19Nin the +2 direction a)“ out D] 3.2 x 104%} inthe—z direction t    t one of the above ; i .63 lite: c at ‘.. Ev 4. A positively charged particle (the dot) sits near a solenoid carrying a current as shown.
If the current through the solenoid is increasing, the particle feels a force
F 4“ WC cents. SFEH‘L
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We ‘” ‘ _ i 1‘ ..
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“if at. t. 54“ I j—l
a. . a. . A] To the right.
B] To the left. gym: of the paper. Into the paper. E] None of the above. 5. A positively charged particle moves in a circle of radius R centered at the origin. If its angular velocity is doubled while keeping R ﬁxed, the magnetic ﬁeld produced by the
particle at the origin yu— b . a... "V _ ; c "‘ «E‘ g...
A] Is unchanged. ~ ﬁr? WE T ~ a w a:
ﬂlﬂcreases by a factor 2. ‘ k i “ts?
C] ncreases by a factor 4. l '~‘ “a B
D] Decreases by a factor 2.  _ r * 3Q " é E
E] None of the above. "‘ R a ” H 1 a: :3. _.,. ,5” gigmgr 6. Two circuits are placed next to each other. The circuit on the right is now pulled away
as shown. In which directions will the currents in the two loops ﬂow? 3“. __ ' k'm‘a
. from? airi
,. i. _ “WVaw 210. “ R2 A] Clockwise injfﬁgcircuit on the left, anticlockwise for the circuit on the right.
*fmnticlockwise in the circuit on the left, clockwise for the circuit on the right. MC] Anticlockwise in the circuit on the left, and zero current for the circuit on the right.
D] Clockwise in both circuits. “we; E] Anticlockwise in both circuits. 7. Which of Maxwell’s equations would be most useful in ﬁnding the aggriﬁﬁeld inside
a capacitor? r we»; t . . irigmauss’ law
B] Gaussii‘llaw'for magnetism
C] Faraday’s law D] Ampere’s law
E] None of the above 8. A parallel plate capacitor carries a charge Q. If the plate separation is doubled keeping
the charge ﬁxed, the energy of the capacitor  at“ ..
A] Is unchanged, V :2 x,.:~' ‘ f/Bj‘lncreases by a factor 2.  E‘“ I “““ Increases by a factor 4. 3 1. __ l ~2 g V 2 ‘fi‘
D] Decreases by a factor 2. U: M a V 3: “1: E] None of the above. '. .
(’1. W'M‘Tl “rttalus 9. The frequency of an electromagnetic wave is doubled. Its speed S'ilnChanged " ‘ Wav’aié‘wﬁg at? ‘i'dt‘gém. in. a Increases by a factor 2. page" ﬂ _ k V 4
C] Increases by a factor 4. \’ ' t: I‘
D] Decreases by a factor 2. ‘ ‘
E] None of the above. CO? 1.5: . “'3 10. A wire carrying current into the paper sits at a distance d from an inﬁnite sheet of
current coming out of the paper. The force on the Wire . at 00601903
,ﬁ a.. ms) .m I 51;: F i independent of d ‘ H? ‘
B] Varies linearly with d. wits 3’ lat, 2.3m
C] Varies as d2. M a 1 I
D] Varies as I/d. IRSVii: E] Varies as l/dz. 4. hm“ v L P‘Wifgm—m u
p ‘ i e draped
ii VT. f”e,.:':' ‘A a "I tr“ J” I“) I ! F
Mile—J w l “ wvl’g‘j“ jz/izsl‘jiwg
ﬂ Free Response Questions Enter your ﬁnal answers in the boxes provided. 1 . A charge 2 nC sits at the point (x = —1c1n, y = 0 cm), and a charge +2 nC sits at. the point (x E 1cm, y : 0 cm). A third charge of mgnitude +1 nC is placed at the point
(x=0 cm,y=2cm). Diagram is not to scale 1)::ng . ' . a »’1,' j, if ‘E  H I a) Find the force on the thlrd charge. ﬂ a?) U r 3: {82%; $2)??? b) Find the total energy (the energy of assembly) of the conﬁguration. 3 ‘ﬁﬂlg In? if H] 4» (W25; u”_‘‘._._........a4......u _ c) The third charge is now moved in a straight line from (0, 2 cm) to the point (3 cm, 0). 5* : {722 ‘2“ . . . .l
Find the total work done on the test charge during thls motlon. « e’” M Force: 32$) N "1‘3; “tilts (PET,
Energy: 31/ j
Work: j ‘~\ {2 [i " '5 as)
_.. z: 337); 0? 31 (lad/0 {lgngQJ 5;"! is
n” / <1” “Yer>22 5m): 3“ 8% a? :1 361? N (plug; in the Same 4%5 35355 V
g :5 sa‘élssa + 3mm g arses/Cogs) : get—«'3': 32, ’1 N W V»; a r
S (12» are let; i)
r“: m U m {a j: govt" at w ‘ ‘9‘!» 'c 33 ‘ —— a W um V; r Me' ‘ c? C? “4x chbhlf‘e L4 J
W ‘ ___ a .. A ‘2
eWe/zﬁ‘ r grim PM “5’47 w: UM}; » 135 “(rise Ox
C. ‘1” rm}. A»? f . v: .7 r
j __ \5 "r it". . : A;_’\. a ‘3 9‘" I I.“ ‘  _ } .«.__.,_,_,_u_m_, t’ at; a. » WA 3 (LT —« or: iii» n; I 2. A long straight wire carries a current 11 = 10.00 A. A rectangular loop of height h =
10.0 cm and width w= 5.0 cm sits near the loop at a distance a = 20.0 cm as shown. This
loop carries a current I; = 2.00 A. I] Yul. Find the net force on the Wire loop from the magnetic ﬁeld of the long Wire. \ {a .... ‘3 ha wan ls: xiii? eff2.1.; \ “I! I: r“ F .. 2 £3 £1; ,
*‘" ~ , j: w _ ' 4 " " ‘ _ .t ‘ C. .a 4 w 2% s. w A w r? *— 3. A coil of total resistance R has N turns, each of length l and Width w. The coil moves
into a region of uniform magnetic ﬁeld with uniform velocity V. a) What is the force on the coil as it enters the magnetic ﬁeld? b) What is the current through the coil as it gasses through the ﬁeld? 0) What is the total energy delivered to the resistance in the period when the loop enters
the ﬁeld? w a “ M k \r j ;
@Lam‘l'z’s Lm'i‘e g” M”. $3  :2 ﬁxing? M N u q {Hui ciit‘ée‘twm all M I l? «*— if eat: I we “I I F: N%BWV)WB: N {3 W 'U" R C): mfgka ﬂ awargy Te re $I§e“iii’f ‘2} {Km ~43
 We; mix =52 FE A“; ' E La? ciE‘slcwtee fraterr '5‘: 17 2’ ftp z 2
We Eater/W ; N B waxith 5 4. An electron is moving in a region of uniform magnetic ﬁeld of magnitude Bo '—" 2T oriented in the +2 direction. At t = 0, the electron is at the origin, and it has a velocity
v0=(3i+4j)mfs. a) Find the force on the electron (in vector notation) at t = 0. b) The electron moves in a circle. Find the radius of the circle (Hint: ﬁnd the initial
speed). c) Find the location of the center of the circle. Force: 3,2Kféﬂ?("4gi43j) Radius: {.qZXIﬁeﬁﬂm 3 (lifaﬂg‘ﬁfﬁmm ,7 :4”
Location of center: x aﬂﬁgtcm, y = cm 5. Four inﬁnite wires are on the corners of a square of side length d = 2 cm.
All the wires carry a current of I = 5.00 A. The directions of the currents are as shown. WWW. 233; genWE"
Drawing is not to scale [32 7: g L if I 34/59 ” if ’?‘ r ' .. I ~ v "“ 3 Wﬂ. Bike?“ : it ‘1‘? #52 " 9$$w§t$ 9+ f: WW6? (/6555 54$ 1 . m ' ~ Mu w ~47 21) Find the magnltude of the magnetic ﬁeld at the center of the square. "' .L ‘ ‘ (:9 ' / b) Find the magnitude of the force 011 the wire on the top left corner. as 7 Magnetic Field: y'f’e’? " if MP F orce: w " it! it, we We; 37‘) F T ‘3?" {a
f i. gig”? \ “ifgin??? “i had ﬁbff Weft/55 331/1 Z‘Fﬂf 9“": Ewi‘miei
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 Spring '08
 Barwick
 Magnetic Field, Electric charge, NC, Henry, E E

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