ES2F10 - 6*.“ 10. 11. 12. Physics 227 — Hourly Exam 2...

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Unformatted text preview: 6*.“ 10. 11. 12. Physics 227 — Hourly Exam 2 Thursday, November 18, 2010, 9:40 PM — 11:00 PM ARC—103 (A—K), PILL—114 (L—R) and SEC—111 (S-Z) Your name sticker SOLUTWMS Q’X Use a #2 pencil to make entries on the answer sheet. Enter the following id information now, before the exam starts. In the section labelled NAME (Last, First, MI.) enter your last name, then fill in the empty circle for a blank, then enter your first name, another blank, and finally your middle initial. Under STUDENT # enter your 9—digit RUID Number. Under CODE enter the exam code given above. Enter 227 under COURSE. You do not need to write anything else on the answer sheet for now, but you may continue to read the instructions. During the exam, you may use a calculator and are allowed one 8.5 x 11 inch sheet of paper with whatever you want written on it. For each of the 16 multiple choice question mark only one answer on the answer sheet. There is no deduction of points for an incorrect answer, so if you cannot work out the answer, you should make an educated guess. If you have questions or problems during the exam, raise your hand and a proctor will assist you. We will provide values of physical constants that are needed but not given, but we will not provide equations. A proctor will check your name sticker and your student ID sometime during the exam. Please have them ready. You are not allowed to give help to any other student, ask for help from any- one but a proctor, or change your seat without permission from a proctor. Doing so will result in a zero score for the exam. When you are done with the exam, hand in only this cover sheet and your answer sheet. Please sign above by the name sticker to indicate that you have read and understood these instructions. Possibly useful constant: 60 = 8.85 x 10’12 C2/N-m2, k :2 1/47reo = 8.99 X 109 N-m2/C2, c 2 speed of light = 3.00 x 108 m/s, ~qelecmn = qpmton = 1.602 X 10“19 C, melecmn == electron mass = 9.11 X 10‘31 kg, mpmton 2: proton mass = 1.67 X 10’27 kg, no 2 4n X 10‘7 Tm = 12.57 X 10“7 Tm, and 1 eV :2 1.602 X 10‘19 J. :> with exam code uh‘alifiko A thin copper Wire of 0.20 mm diameter carries a current of 2 A. Copper has 8.4 X 1028 free electrons per m3. What is the drift speed of the electrons? a 6.06 x 103 m sec .. ‘ elm Aha“)! wows) bl 2.1 x 106 m/éec I (A) ' $11611.) “:1 t 3) v _..... .. . ,. c) 6.11x10‘41n/sec U. _‘ z ‘9" gNA " Ll,LHO'W)C3.‘Q¥IDL5)CEGym.“) e 1.48><10 m/sec = uJHO'BMLS A cylindrical copper Wire (resistivity = 1.70 x 10’“8 Q - m) With a diameter of 1 x 10"3 m and 0.01 m long is used to connect two points on a printed circuit board at room temperature. If the current in the Wire is 10 mA, What is the potential drop across the Wire? a) 0.54/1V V=IR R: A“ am; ~ "2‘ 3; 3:61am V: 11A: 1: (Wig—91):; renew . m 2 ‘ e) 5.4 mV A EU”) A battery has an emf, 5, and an internal resistance, 7". When a 59 resistor is connected across the battery, a current of 2A flows. When an 119 resistor is connected, 1A flows. The internal resistance of the battery is: @ 2:2(1’4’53 azicrflq C) 59 ZP-fi-‘D: P4'l‘ (1)100 r; {LIL e) 79 Consider the circuit in the figure, With 24.0 V across the network of three identical resistors each With R 2 16.0 9. What is the reading of an ammeter With resistance 3.00 Q, When it is inserted at point a at the right end of the 3 resistors? a) 0.75 A 1.0 A | ::X__ at“)... R ‘7‘" +l$ R Quay“ “1" {2+1}; = 0.8‘IA = 8*“ 5. In the circuit shown, the current flowing through the 0.5 Q resistance is 0.80 $2 1.2 Q :1 U a) 4.0A 5"“ “EHQU‘J‘L‘ 8v- 3% 5mm upH—asg ' “UL c; 0.8A 0"" “‘2— .512. r2554» . . . I d) 38A “We 2J2. abbwalw . _ ' {L 8) 80A Vcsfsl-or, wfw HA hawk 3v, 2A 60 rune/vb C: 3 .51 '5'- 2 H“: ~ 2.53:: 2. =5 :=~3.2A —> 11-qu 6. A resistor dissipates 0.50 W when when the potential drop across it is 3.0 V. When the potential drop across it is 1.0 V, the same: resistor will dissipate: a) 0.5OW ? __ Vi: 12.11:“th b) 0.17 W . f" .i , - c) 1.5 W .1) R 3311/? = 31/95 :‘ ‘83,?" Pa:- V'Ll‘z.‘ ‘AB‘z‘D-s'gw e none of these 7. A 1 MP capacitor is charged up to a voltage of 100V. The capacitor is discharged through a 10 S2 resistor. What is the current flowing after 30 microseconds? _ 71:11; am 3: “I08, 3) 23A to >VIR' = \UOV/lpaL'J—(OA . _‘_ I- _ d? 0.05AA I 2 WA ( E”... 30W) /\° 5') — 0.57% e 9.5 g 8. An electron and a proton in the same uniform magnetic field trace out circles of the same radius, one clockwise and the other counterclockwise. What is the ratio of electron to proton momentum? P:‘Q&L’:f~ c) (5.4 x 10-4) ‘53 ‘5 B d) It depends on the radius of the circle. e) It depends on the magnetic field. P ,. 6 Br 9. Which of the following statements is false? a) The magnetic force does zero work on a charged particle moving in a magnetic field. b) A current—carrying closed loop of wire in a constant, uniform mag— netic fiel 'c force on it. lg A charge moving through a magnetic field always fee s a nonzero magaa am“ force. *0 (rm By The magnetic torque on a current—carrying coil of wire is zero when ‘ . the magnetic field is perpendicular to the plane of the coil. “4“; ~ e) The net magnetic flux through any closed surface is zero. 10. A wire of length d = 0.5 m lies along the x axis and carries a current I = 2.0 A in the +9: direction. The magnetic field in this region is uniform and in the my plane. The resulting force on the wire is 1.0 X 10“2 2 N. Which of the following must be true? a) Nothing further about the 1? field can be determined. we.- b)' By=~0.005T '6' a. 3; 5i {é Marsh ‘1“, ,Je .D‘. c) By=0.005T « A .a- mag?‘ Ar. 63%,,“ d) By=-0.01T mat: x )c B \> m 3 , y = 0.01 cmwfi- WWW- “ cm paws—yd" 11. A circular coil of radius 40.0 cm with 20 turns lies in the x~y plane in B Z :: D uniform magnetic field of magnitude 0.5 T in the +9: direction. The current in the loop is 6.0 A (in the direction shown in the figure). The magnitude and direction of the torque vector acting on the coil is y a) 1.5 Nm in the +2 direction b) 30 Nm in the —z direction c) 1.5 Nm in the +y direction a I m in the —y directio ) e none 0 t e others The z—axis is coming out of the page. 12. Two long straight current—carrying parallel wires cross the 1: axis and carry currents l and 31 in the same direction, as shown. At what value of a: is the net magnetic field zero? a 0 BS—oekfis Cube. “1 bp‘flbfik b) 2 chlneL'wa5, AdeZ cam X dc) 10 (RM +9 01 e) 13 w\w§s‘u5\n5 8:- fi- ‘gz k-J. 4"" x: 13. A long solenoid of 400 turns of wire is 15 cm in length. It carries a current. of 4.0 A, and is filled with silicon steel (K = 5200). What is the magnetic field inside the solenoid at its center? a) About 2.0 mT B -_. K “a H I b About 13. mT _ '122 c; About 20. T “SW—0°“ “"7"” fl>( us) Go e About 10. T 14. In the figure shown, a conductor consisting of a circular arc of 45° with radius R and two wires attached to this arc going radially outward (and effectively infinite in length) has a current I passing through it. What is the magnitude of the magnetic field at point P, the center of the arc? 3») (Mo D/(ZR) b) (#0 0/033) c) 0 W ' MO I (47rR) The, radial ‘65; £9 140+ Mgbul-a'b msacfl a'f' P. (I? Evatwy-kuiw 00mg, {0 ix; :0.) (Alglduwr— 1/? bit—aloof, rm .mfw C(91)“ \90? WNW 31m: Milan, $0 15. A cylindrical wire of cross sectional radius R = 0.0010 in carries a total current I = 20 A, which is uniformly distributed inside the wire. At a distance 7" = 0.00050 m from the center of the wire, inside the wire, what is the magnetic field strength? B :_ MOI“; ~ Ma y I x "72.) w .a) 0.0020 T :2 Wm 21-”. "T 12‘ b .00064T 4) ‘ “a 0) 0.00401“ 9:. 41231. .,. _, (“WHO (20) ENG d) 0.0080T “'3’ 7"" Uh“) e) The magnetic field strength inside the wire is 0 T. B 2* urgr. 16. Two long parallel conductors are separated by a distance of 0.05 m. One of them carries current of 6.0 A and the other 7.0 in the opposite direction. The force per unit length the first wire exerts on the second is: a) (1.7 x 10—4) N/m; attractive F \_ M“ I I\ b) (3.4 x 10“4 N In; attractive \ le- T 2"" . m; repu s1ve _ d) (3.4 x 10‘4) N/m; repulsive 2&1?le '1) LL30” e) none of the above (:5. “0.2) ¢ Mum“ Pavauel meuks GUM". “Lt A4“ Pumud cuvas “1951‘ ...
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This note was uploaded on 01/04/2012 for the course PHYSICS 750:227 taught by Professor Ronaldgilman during the Fall '11 term at Rutgers.

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ES2F10 - 6*.“ 10. 11. 12. Physics 227 — Hourly Exam 2...

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