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Physics 1 12 E ?
Summer Quarter Quizﬁ Problems 4 and 5: Two charges q1 = — 400 11C and q2 = + 400 uC are fixed at the bottom vertices
of an equilateral triangle with sides L = 80.0 cm. I,“ E 4. What is the direction of the net electric ﬁeld at the top vertex? 4&4' Elng: E 2414: .62X106N/C C E i <5]? Wall/vb?) gum/:2 b) 9.73 x106N/C x
c) 1.12>< 10’ MC y L ‘
d)2.25 ><103 N/C ﬁrearm 7,7’5‘x,,76;yé £3 in u‘u. b) he ﬁeld points toward the left side of the page.
K c The field points toward the top of the page. d) The ﬁeld points toward the bottom of the page. e) none of the above ﬁhe ﬁeld points toward the right side of the page. :2 Ewlm 5. What is the magnitude of the net electric ﬁeld at ﬂie top vertex? Eng/1 2 E Méoc; 5 lama; Physics 1 12
Spring 2010 Group Work Problem #1 [Based on 18—P34.] 1. The ﬁgures show two situations in i which charges are placed on the x and “5‘0 “S +1&uc
y—axes. They are located at the same : 1
distance from the origin. Without : 6 ﬂ 0 c l l a C
calculating any numbers, does the +Z&E____{____'_3 0" 1 gu___:____“_'qp
electric ﬁeld at the origin for situation I : 1 l
(a) have a magnitude that is greater : l
than, less than, or equal to the ' a
magnitude of the ﬁeld at the origin in *50 PC
situation (in)? E") U" it s ‘ g ’1“ L [a a/‘b {lee/Y —~—l4ﬁ'§ﬁ‘
W Sqmen 2. If each charge is a distance of 16 cm ﬁ’om the origin, what is the electric ﬁeld (find both
magnitude and direction) at the origin for situation (a)? Eu "Fiji; 1 O'LX/OST/c in 'i’lv, {Y oil/Gaff?“
r1 . q : +\
9L 2 [,OS‘XIDFY/L m 1h: +y 0‘ rep ..,.. E3: L? (aHOéT/c in
E. . EH41: Ltﬂxfocr/C EH =1/(1.uwow/autﬁax/céi)‘
2 T
EM l'gxm /C’ 956° {Haﬁz 3. What would be the acceleration of an electron (ﬁnd both magnitude and direction) at the
origin for situation (a)? (e = 1.60 X i049 C, m = 9.11 x 10'31 kg) Film‘GE—h a: ‘4 F=q£ m m +K attraction SM“, '= LLLiktO‘lm/‘SL L 1. Two point charges are arranged along the x axis as shown in the ﬁgure. The total 2. If the work required to move a +0.35 C charge from point A to point B is +125 J, What is the magnitude potential due to the two charges is equal to zero at some x value between the two charges. of the potential difference between the two points?
What is this x value (measured from the 2 pC charge)? ' A V
357v W: AE’PE *‘ +2.0 pC —5.0 uC b It >
. zero V0 S
0—O—> = C><Akf
I I x e. 88 V ‘ 3 g 0 1.0m d.44V EJZAU : 397V id“ x : @Mrw We; V=o e. 180V O‘Sgc'
‘ in m (* ZM + (f S/(A C.) I: q 3, There is a potential in a certain space that varies as a function of position. What best describes the
._______.._ motion of a free body that has an excess number of electrons on it? X 2 E 1 ‘ x I” 2 _2 r 5 X a. It will move toaregion oflower potential N0 " WQ°‘0L+‘(V¢ QL’W‘ﬂa‘i Sefk bl by?
32‘ ~ (:32 Z‘ O ' X 2 b. It will remain ﬁxed in space unless it is givenaninitial velocity ‘— Wo “(new M 8— lice
m X S' 77.. ’3: Qt m c. It will move to minimize its kinetic energy — W0) am a ngg f0 @ It will move so as to reduce its potential energy \ (
2. A charge of +1000 uC moves from position A to position B under the inﬂuence of an 3 ' electrical ﬁeld. The electrical potential difference between the two points is VA —VB = 100‘0 volts‘ What is the work done by the electric force? 4. The potential at point A is larger than the potential at point B. Which of the following is false? Wﬂ Ll MALC— A ’5'?) a. There is an electric ﬁeld pointing from A to B * >< It would require positive work by an external force to move a negative charge from B to A 1" (at " :2 00 V) c. A positive charge would gain kinetic energy moving freely from A to B. ﬂy“ 1 E 1 o O d. For a positive charge freely moving from A to B, the sum of its kineEtic energy plus electrical potential energy is constant —' lm g sz33 '— 4/0 We
a 3. A particle with an unknown number of excess electrons is placed at rest in an electric C > 5 c9 i ' (LCM/Lye. WW lam/W (a 1L” ‘ ﬁeld. Aﬂer it moves through a potential difference of magnitude 1 x106 Volts, the kinetic Nzﬂw CU 6 '  a} 8 energy ofthe particle is measured to be 9.6 x 10'5 Joules. How many excess electrons % fl 2 a/i‘tl/e Q r M I M4 “A” ‘ g at”! {7: were ontheparticle? (Em M VG (Alan/c WWW”? kE. :4) , kE. = ALWJALI. arrLA tAuM..:..,. \
5. T NU v v F I V d long the x axis as shown‘in the ﬁgure. At which of the t'ollowmg 6h, I Cd valISeIsjzflxisathgee:1::13225:nti:1 equal to zero? z a. +0.05m
« G
cirGXlU 53‘ =’ Q (1)00 b. +0.40m = 9 (0K10”C ©+0‘29m +2.0uc In 5.0p.C
N chh l q i d. +0.54m .——O——> ~
2 u E — .__a x
"l ~ q) u < 3 e, +0.71m (I) x rolm ﬂew/m ﬂgwrwﬂc
Ne. =‘ W = (“X”) KZNO'G ngexm'Q =0 / Coated KM (c)
X _ ‘____,_)
lQXiU HG lx 1...;
4. A charge of Q is placed a distance x:+ D from from the origin. The potential is measured a X
to be V0. What would be the potential at the origin if the charge changed its sign but not 
its magnitude, and the charge were moved to x= D? O 7" 2 ‘ ‘9‘ x 5 X e \ 2K {OlM/LL rﬂic
VMM‘ at 0W6“ £2 MMBE from ciao. t 13 chair]; I, Find the acceleration of an electron that travels in an electric field of 500 MC. f. er Ci/lnno‘e 6) span} \ld—e ~Va {r 8 a) 7.02 x 1018 m/S2 [l ;
X=TD m ~‘D ail/£4 name , o b)3.13><1o21 I'm/52 ‘m M
c) 5.49 ><1032 mis2 Ar V ,‘ 7 V
5. Inlthe presence ofa. negative charge, a free particle with an excess number ofelectrons @878 x 10‘3 mfs2 at »_ (I ’ b c x "c C 5 “V I 4 J 9/ 8 g x/ L. 0%“
W111 move such that: n s e) none ofthe above (7, if X/ y’ 3 I 6 l _ l L
"The, n q wLl ClAaV‘erJ ar‘i'icla rid! . I A
. I 2. What IS the kinetic energy of an electron that has been accelerated from rest through a
may 9 H0 mac marge its lhAl‘I a one r tjj potential difference of 350 V? V
. .— r 'n».. I ;" $L'(
. : Apt , any») 3;
Mel Fetal Dice L'l’s :Eo'l'lm'l‘lﬁtl “lava: a 2.19><10“J Kt { / I? _ 47
‘ b5.60><10’”J , (HM/J alarm/l: 5.6mm J
c) 350 J
1. A 1.0 [4C point charge is moved from point A to B in the uniform electric ﬁeld as shown. Which one of d) 3 39 x 10.7 J
the following statements is necessarily true concerning the potential energy of the negative point charge? '
e) none of the above
a. It increases by 6.0 x10’6 J. 3. In the ﬁgure, negative charge 4 = —9.00 11C lies at the origin, and each of the charges Ql 2
It increases by 90 X104, 1 E: 3 Wm ,3 +3.00 uC, Q2 = +5.00 uC, and Q3 = +7.00 uC are 5.00 cm from charge q. What is the magnitude
,6 ///l of the net force on the ~9.00 uC charge‘.7 . ‘_ 5 , 5 r
c. It decreases by 6.0 x10 J. 3.6m 2.0111 2 a k (qxﬂlf‘c)(’§>(/L L) r 0.0 t M
"6 ’ 162 N = " ' = —/ f,” ...,,g
Wtdecreasesby 9.0 x10 J. AK:__M3_0m._‘[email protected] ﬁlnN F/ fl] (plus—M); c Q1
e. It increases by 10.8 x10’6 J. c) 485 N f, : 77, l M (1)425 N [g a. k (INA/(“mi 15 if“ Lies{ enoneoteaove F 1 ; ,
gram is Laban at $3 @ t f“ h z 7. .1
@rm‘iml re Pew/Vie, €m o ' ( .. 2 ~ :4 LJ'f.‘ =— "’1 F} t a k "7Kru VA Va VA VS : Ea/(ﬁan‘ﬂMf CW 37
[Aet’fjelig’wl=Qi.x10'0)<qv3 = + Wm ...
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 Spring '10
 Any
 Physics, Electron, Electric Potential, Potential Energy, Electric charge

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