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Unformatted text preview: PHYS224 Name Einal Exam
sUMMER 2005 I
Show all work. (9,0 Have a good work term. MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) A positive test charge q is released near a positive fixed charge Q. 9 Q .
“iced As q moves away from Q, it will move with ( A) constant acceleration. Charge\  B) increasing acceleration. '4 C) constant velocity. F \1/ as d" 5 law (Q [P ) decreasin acceleration. f ._\
(g g V d m (1
2) A proton is located at x = 3.0 run, y = 0.0 nm and an electron is located at x = 0.0 nm, y = 3.0 nrn. Find the force on the electron. due Hie p rot‘on A) 5.0 x 1018 N :l B) 5.0 x 108 N C) 8.4 x 1015 N @13x 1011 N
1Fl= '43? :1; 2 12
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' ‘fCwaD't'z‘ééJ q. PHYS—224, Final Exam , Summer 2005, page 2 3) Two 4.0 cm x 4.0 cm electrodes spaced 2.0 mm apart form a parallelplate capacitor. Inside the capacitor the
electric field strength is 8.4 x 106 N / C. What is the charge on each electrode? A)99nC _.: p ,. :Gt/
B)59nC C /Ec {/2 A
@120nc 2 0/2) A
D)54nC . ° (3Q = so It E — (3.85x¢0*"2)(qx Io‘lfﬁrquw —— quwo‘70 4) Two equal and opposite charges a certain distance apart are called an electric "dipole". A positive test charge
+q is placed as shown, equidistant from the two charges. F++ ' <1 (test charge)
F \ G) <3) Which diagram below gives the direction of the net force on the test charge? . @M 2?“ 
B) QM 5) As an electron moves {min a‘highpotential toaflowfpotential, its electrical potential energy ‘
A)remainSConstant. ' l ' fi V '7 ' ~
decreases. 7' , r. I . 7‘
E 7.. B) ‘
@mcreases. ‘ +  '
* ” ' high low
[f9 leon would \L in U] PHYS—224, Final Exam , Summer 2005, page 3 6) A charge of 8.0 HC and a second charge are initially far apart. If it takes 20] of work to bring them to a final
configuration in which the 8.0 “C is at x = 1.0 m, y = 1.0 mm, and the other charge is at x = 1.0 mm, y = 3.0 mm, ﬁnd the magnitude of the unknown charge. ‘3
A) 2.78 MC U = M. $1 $2.
B) 1.12 uC r @0 56 ac _ U p
D) 1.12 nC 6‘ 1 ‘ a _ (zoﬂleo‘ 3)
(Qxloqi (Swo‘b) = 556x10‘7e 7) Three capacitors of equal capacitance are arranged as shown. The voltage drop across C1 is 90.0 V. What is the
voltage drop across C 3? @mov B) 90.0 V \n/
C) 270 V D)360V".. IQ N
p
E
A
f3
h)
ll [I
A .
PJ‘
1.
0]—
N
I—\J PHYS—224, Final Exam , Summer 2005, page 4 8) How much current will be flowing through a 51.0 m length of copper wire with radius 5.1 mm if it is connected
to a source supplying 56.0 V? (The resistivity of copper is 1.68 x 10—8 Q  m.) A)33x108A 1_
B)3200A V=IR R: C)190nA I = L ‘ m VTrrz @5300A_ R ‘ PL = Tyr— : (SéX'rrKrsilx/o‘BJZ
( 1,58x/o‘8)(5/) = _)
9) A wire carries a 3.0 A current along the x—axis through a magnetic field B = 3.0/i\+ 9.0/j\T. If the wire
experiences a force of 23.01: N as a result, how long is the wire? A)2.6m —‘__ —“ "‘ ‘ Z‘ A 4;
B 0.85m F “LLLB _ 'L 3 %> O
C)0.81m ‘ 3 q 0 10) A ring with a clockwise current (as seen from above the ring) is situated with its center directly above another
ring, which has a counter—clockwise current, as shown below. In what direction is the net magnetic force exerted on the top ring? /.
{H'ch Sldcl‘. ~ :.‘.'.‘:.:.j_.’i?r_‘1§f iiiéP'Posilre" dimes/1+ ‘ em/ m3 is; " 'B)downwardfr 1. ‘ ‘ C) Thenet force is zero. ' D) Impossible to determine ' PHYS—224, Final Exam , Summer 2005, page 5 11) A square conductor with 1.0 m sides is placed in the yz plane. The magnetic field in the area increases
uniformly from 5.0/i\T to 9.0’i‘T in 2.0 s at a constant rate. What is the emf that this changing magnetic field induces in the conductor? d I}
2.0 V : Hie
ﬂ 1 {— 7” @ C) xiii/V :_ (l)z( j— P) D) —4.5 V ' X :"QV indLLLeolI,T cw as seen ’t
by observer loo? 12) A circular wire ring is situated above a long straight wire, as shown below. The straight wire has a current
ﬂowing to the right, and the current is increasing in time at a constant rate. Which statement is true? 2 Ewdnuﬂ iv OFF”;
Linc changing great) Emg amended by
‘lhc. wine.Ii’l\
as I T. [—5 A) There is no induced current in the wire ring.
B) There is an induced current in the wire ring, directed in a counter—clockwise orientation. C) here is an induced current in the wire ring, directed in clockwise orientation. SHORT ANSWER. _Write the word'or phrase that best completes each statement or answers the question. 4 Q 13) A closed, circular loop.has a‘cur'rent‘flowing through it. If a second, closed, circular loop with the same radius ‘
approaches this loop along atommon axis as' shown, in what direction will a current ﬂow the approaching ‘ "
loop? Draw Variarrowron the approaching loop and write clockwise or counterclockWise... _{ ‘ " sfﬂﬂ€9f5¥¢€5, _ . _ H ,..e;;y H;.¢3Kf alodcwige reef? ‘ 4:: ‘ _w1,w. passedﬁ ~PH93:224)*‘ PHYS224, Final Exam, Summer 2005, worked out problems
ri H below 14 A negatively charged particle is moving to the left: Irectly above a wire having a current ﬂowing to the left as shown
below. In which direction is the magnetic force exerted on the particle? I Q) upward B) downward C) into the page D) out of the page E) The magnetic force is zero since the velocity is parallel to the current. WORKED OUT PROBLEMS ‘Gti tinder U‘ ' # 15. A solid, conducting spheregf radius R has a surface charge density of a. Starti g with Gauss’s Law
and showing ALL steps, ﬁnd the expression for the electric ﬁeld inside and outside the cylinder. Graph the
Electric Field vs. r. ’ (yeah ﬁrm/2,, = CW; 34yde owe E constant on 638 CW Er<R=? E :0 C%ena=0 [96cm6 W
Mediauge is on #ie standard) Er>R= . PHYS224, Final Exam, Summer 2005, worked out problems #16. Two point particles, Q = +7 ,uC are located as shown. The points A and B are (0,4m) and (0,0)
respectively. Q 62
V: + = 1K7
a. Find the change in potential VB— VA.
b. If a point charge, q = 3[IC of mass 4 x 10"3 kg is released from rest at point A, what is its speed at point B?
l
a. v3 = 2m [a]
‘ l
VA = [E42432] V2] : 2. L __ _J_
4m V6~vﬂ=gu<a l: 3 s] = :2 (quot) (7x10 6) [J5 ~39 —— O t. A44=i3Av= ﬁmttrsl—ﬂf)
m3; LL”? mAV '= 12(‘3HU6M'L63HDH) :0 an to“? = /.5_C}'vtll)3m/_S # 17. A uniformly charged rod has a linear charge density, A and total length L. Starting with V = j qu/r ,
let x be the variable of integration, and make the appropriate substitutions in the integral to ﬁnd the expression for the potential at point P. Use the symbols as deﬁned in the ﬁgure. If you need any additional symbols,
' CLEARLY deﬁne them in the ﬁgure. You do not need to solve the integral. PHYS224, Final Exam, Summer 2005, worked out problems t vector notation, at point P due the long de and direction in uni
at the origin and point P f the page. The currentcarrying wire is #18. Determine the magnetic ﬁeld, magnitu
s 1.5 A of current out 0 straight wire that carrie
is at (4m, 2m). A (sf/MID—8 Esinae.e° 2 + 0.05.26.65
6.7!“sz [— 04/472 + 0.24qu
' ‘30 r3le 4' EOHT Il th an inner radius 5.0 mm and an outer radius of 30 mm conducts a 4.0 A current #19. A hollow cylinder wi
magnetic ﬁeld at a point 11 mm from its center? Start with 'out of the page. What is the magnitude of the
Amphere’s Law and show all steps. @Eo d5 z/aojem.
E Constanta} on ‘
Babel5’ . ‘~ {1 . BJZ'trr vac : ' 12w , . _ . r . . ...
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