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Unformatted text preview: PHYSICS 1E03 TEST March 14, 2005 Name Ed l 54 Q3“ ‘5‘: Instructors: Student Number
A. Jopko (section C01) N. McKay (sections C02, C03) Mac email: @mcmaster.ca D. Venus (section C04)
K. Sills (section C05) Instructor: Write your name and student number on your paper before you begin. Multiplechoice questions are worth 2
marks each (only the answer is marked), and problems are worth 3 marks each (clear solutions required). Only the McMaster standard calculator (Casio ﬁ991 ) is allowed. Notes and formula sheets are not permitted.
Some formulae are given below; if you use them it is your responsibility to know what they mean and when they can be used. Earth’s gravitational ﬁeld: g = 9.81 Inst Electronic charge: 6 = l.60><10‘l9 C
Electron mass: me = 9.11x10'3l kg Proton mass: rm1 = 1.6Tr'><10_21 kg
Coulomb’s Law constant: it. = 8.99x109 Nm’rc2 Permeability ofvacuum: tr, = 411x 10‘1 TmzA'l Permittivity of vacuum: so = (4rd:e )'1 = 8.85MB"l2 Czthrn’2 2 1
F=ma 0,2:— J=§=nqu=05 Rsedes=Rl+R2+m
r
K:%mv2 p=lf0t R;;ﬂlc,:Rfl+R§l+u
pL
U:*WCO”"=—IF'dr lie—:7 CWBIZC1+C2+'H
F=qE V=IR 03m =01"l +C;’ +.
Ezke—ii‘ q(r)=Qoe—f/RC
r
 1 _ _ ( 4330)
(DE "4E.dA“;_‘Qenc '4nkeQenc 9(0—Qﬁnal 1—8
0
CF #0 I‘dst
: =——=27dc F: B dB=——
plane E 280 err qvx I 4” r2
conductor: E=i=47dfea F=IL><B tj‘BIdEauolmww
5'0
[Jqu de—Eods r:1AxB:;1xB straightwire: 82:0;
:rr
q . Q . «
V=k  (j. 2—— solenotd. B~ :11
gr AV #0
A
1 2 u _ C—Kgﬂd
1——9 10 11 12 13 Total (18) Q) £3) £2) (31 (30 continued on page 2... Page 2 of 8 pages Part A (multiple choice): Print the letter corresponding to the best or most nearly correct answer in the
box beside each question. Each correct answer is worth 2 marks. 1. A fuse “blows” if the current exceeds 1.0 A. It is made of a material that melts at a current density
of 300 A/cmz, What is the diameter of the wire in the fuse? A) 0.98 mm :9», __ ’1: “L B) 0mm (“JP n/éawz if I ‘ o enoug Information. Need to know the length of the Fuse wire. answer C. 2. The resistance between points A and B is A)R i .
£93,212 ‘1 2% V2 answer R D 3. A rectangular loop of wire in the xy plane carries a current I ﬂowing clockwise as shown. The loop
is in a region of non—uniform magnetic ﬁeld 131:10'5 yj T, where y is measured in metres. The net
magnetic force on the loop is ",... ‘ —. . /I‘——w ' I.. .n... _.  "_ 5‘ z A} parallel to the z axis..._3t
“parallel to the x axis
C) parallel to the y axis
D) zero.
y .
answer ' i": i
4 J i” i
q.__
x
I continued on next page... Page 3 of 8 pages 4. A capacitor with a dielectric slab between its plates is charged by attaching it to a battery. In order
to end up with the largest potential difference across the capacitor, it is best to A)....ﬁrst.rsn10_ve the dielestris #399. battery
4""Bufﬂatsconﬁééfthé‘Haitérmhcumoﬁthscdislsstris.4A ‘ “5) Either give the same result in the end. answer 5. What fraction of the current I passes through the resistor “r”? 1 I I" R
@ﬂjﬂrwﬁﬁ ~ ,, a . .,. ___.
CB?) Melvin V t I»; Q ’ 1w " I r ‘ (A
D) R
l'  n...
2.» g; _ a»? . e ' ... l a, r f R answer 3 6. What is the time constant 1: for this circuit? C
é)__J.f.6_ _RC R
S? (:2 my? 8 :T J, 0
WW
C answer '13 continued on next page... Page 4 of8 pages 7. A straight wire carries a 3.0 A current along the xuaxis in a magnetic ﬁeld B=0.30i +0.90j T. If the wire
experiences a magnetic force of2.3 N, how long is the wire?“ A 2.6 m 41. _, : .. I“ . k, f
’B) .... 1 1} it}. : , 7? , r', ,{W 3;
"0) 0.31m ‘ D) 0.64m [:7 :3? ’33? k1 BHSWCI' '73 8. An catparticle (2 protons and 2 neutrons bound together) has a mass of 6.6235(10'27 kg and moves in a circle of
radius 5.0 cm in a uniform magnetic ﬁeld with strength 0.03 T. What is the acceleration of the particle? 0h» _ . 4 frat if” '— “* Vt . 1L5 ‘ a...’
A) 0
B) 9.8 HUS: 2 2 53 :3 I”
C) .IIUIS_H_ pm I" W 9”“ i l :7 §.a Hf} {p @Toztxlo” mlsz “a, W vi: " it *1“ n... r
ﬁnwwmwnwo—ﬂ" W Answer D 9. Before the switch is closed, the capacitor has no charge on it. The instant after the switch is closed,
the current I is R1
A) 0
B)_ 81'(R1+R3) + 5 _ C R2
mama) l !
{——.——
Answer I (3. continued on next page... Page 5 of 8 pages Part B (Problems): Write a clear solution showing how the anSWer is obtained. Each problem is
worth 3 marks. 10. A square rod and a cylindrical rod are made of the same copper alloy and cut to the same length, as shown in the diagram. When a potential difference of 1.70 V is applied across the length of the L
cylindrical rod, it dissipates 10.0 W by 28 I L Joule heating. What voltage should be applied across the length of the square
rod so that it also dissipates 10.0 W? 23
Z
T3 ~ T \i t V J P "‘ L» answer /. ‘5) gab/5 continued on next page... Page 6 0f 8 pages I 1. Two very long wires carry equal currents of3.5 A into the page in the diagram. The wires are at positions
x = ~d and x = +d on the x~axis. Find the magnitude and direction ofthe magnetic ﬁeld at the position y = +d on
the y»axis when d = 7’ em. I _...,‘ a? “E 1.
, <1: i “
EJ4§°
RX,
E. 7:}
ix) ; f; ‘i "6 i' ‘r. W b H
; . x ' . _
j 1. 2 1 «2 r1 answer
Magnitude: /(). 0 A, T ’1 Direction: 7 {faf "’9 continued on next page”. 12. Find the current 1;, when R=189 and 8:9.0 V. Include correct sign
for direction deﬁned in the diagram. Li’mli‘ér 9 3* I i T
iU'E‘ia C. or
r 4 "2"" .e g t 3.1 .
36‘” 1 L + 29 13
level? :2 (vie/.1 ‘ __.. 19(
_.. ,_ m r  .... *2
3 2 a? 3.1 “£8.13”
D¢©l€seﬁéij' #:311731qu 1:”; Page 7 0f8' pages ("i "x
.. {‘f j
2/
33 ‘ 5’ “400wA
if
at 7" 4 I’m} "’9’ ~I.“ F131 f3 : ~— 3.100 wage
answer we Boowﬁ} continued on next page... “1):: 114‘ '. Page 8 of8 pages 13. Use Ampere’s Law to ﬁnd an expression for the magnitude of the magnetic ﬁeld at any
radius r inside a cylindrical wire of radius R. The wire carries a current, with the current density J uniform across the crosssection ofthe wire. Show the path along which you apply Amperc’s Law, and provide explanations for why you have
chosen this path. ansWer RIMS" Eli/(“7" END ...
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 Spring '09
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