Exam1_59955_sol - Name: PHY 3l7L February, 22, 2007...

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Unformatted text preview: Name: PHY 3l7L February, 22, 2007 Signature: ,Exam 1 Unique number 59955 Instructions: 0 No notes, textbooks, or similar aids are permitted. 0 Use the scantron answer sheet to provide the answers. Follow exactly the directions how to mark it. Write your name (last, first), UTEID, course name, unique number. Sign and date it. Mark solutions for all problems. Mark your answer sheet using #2 pencil. Mark only one answer per problem. If you need another scantron, ask the instructor. 0 There are 16 problems on the exam. Every correctly answered problem is worth 6.25 points. An incorrectly answered problem is worth 0 points. 0 Unless you are ready to leave at least 5 minutes before 1:45 pm, please, stay in your seat until all answer sheets are collected exactly at 1:45 pm (i.e., you have about 75 minutes for the test). 0 Any questions you may have about the test have to be directed to the instructor or a TA -- - no conversations and/or collaborative work are permitted. 0 You may use the blank sides of the handout for notes and calculations. 0 Some equations and other information that may be useful on this exam are provided on the last sheet of the handout. You may detach it during the exam but may not ask questions about it. You will also have to turn it in with the rest of the exam handout at the end of the exam. 0 Sign the exam handouts and return them with the scantron form. Page 1 "610.» 9’ 5 I it , J h 1. An isolated charged point particle produces an electric field with magnitude E at a point 0.5 m away. At a point 2.0 m from the particle the magnitude of the field is: @ Let & bi W at ‘k.*"al , 2 C) 415 E = -3-- Etoflf ’1’" =4 3.. 5(1'44mt4) D) 15/4 W5“ “"0"” 7"?" : ,1 2 ~ E) 5/32 F _ .1 (11.6) E 2. An object is 20 cm in front of a converging lens of focal length 40 cm. The image is: A real, erect, 40 cm behind the lens, and two times bigger than the object virtual, erect, 40 cm in front of the lens, and two times bigger than the object real, inverted, 20 cm behind the lens, and the same size as the object D) virtual, inverted, 10 cm in front of the lens, and half as big as the object E) real, erect, 80 cm behind the lens, and four times bigger than the object . ' :Bvir'tc ur.v('(3'|“;\ S=40¢M r:wgm ‘ ‘ \ \ ‘ ‘ :5‘545‘.” t<0 vt—\ 'l»—'t--"':-_. . Via-\KuKWS 1' 'i V ‘° 1° ‘5 m=-'/§=Z>c>::¢°¢tt,twowi A 3. A solid metal sphere of radius 1 m carries a negative charge and is at a potential of —50 ‘7')?" V at its surface, relative to the potential far away (which we assign the value of 0 V). The potential at the center of the sphere, and 2 m from the center of the sphere, are: 6;) —50 V at the center, —25 V at a point 2 m from the center ’?.wc;\ kt eat mu; c. ) 0 V at the center, —50 V at a point 2 m from the center VuvwhA “g u 4 K“ C) —50 V at the center, —]2.5 V at a point 2 m from the center . K K “A «‘3 «mam, D) 0 V at the center, 25 V at a point 2 m from the center s "A j? =7 -* 5‘0 Vet WW E) none of these \I: l A $0 “mu 0" Q“, “mgjowng “1“ r V-sV/za-zs-x/ @ 4. For a particular arrangement of a He—Ne laser incident on a single slit of width 0.20 mm, the first minimum adjacent to the central maximum of the single—slit diffraction pattern is located on a screen a distance of 1.0 cm from the peak (i.e., center) of the central maximum. If the slit is now replaced with a slit of with 0.10 mm, with all other things remaining the same, what will be the new distance from the first minimum to the center? A) 1.0 cm {saw-\Mt—z as'mg : M), we, WA @ cm 98 for Baa-AX 9 $33.82 khfi r: ) 0.5crn AF 49 3 k _D D) ncm a€w8:)\ E) none of these 065 v“ > (\A/ A: D va— g= 5° 1t «Mam. Page 2 5. Two tiny green dots are located at the bottom of an eye chart. The distance between the (b dots is 1 mm. Approximately what is the maximum distance at which a person can distinguish between the images of the two dots? Recall that the pupil diameter is about 2 mm and the index of refraction inside the human eye is about 1.3. You should approximate the wavelength of green light to be about 550 nm. A) ]m i >\: so hmzs.($déqw\ sumo 9 % :tM93-5k929 4 m A =1.—.—: 2. H5.“ A . ~ .. r - A-Rtuh an. \. ksmn\\k team. @ 9 m ‘ cm I: 31‘0"“ ‘6‘” 9 1:31} fittuu‘lrlt‘zk RS .Mb-lh if D) 15m n:l..3 " 'D . . . CK . ~..\. “g Mvfit h \osu )ubttki/n E) none of these, because there rs nolrrnit «vii-Mum “‘4‘” 7‘ ‘ . .3 a“ .\ :2. N A “3"” “‘° ‘3 4 m " M9: 99. Lzzk 0.21.30? "(9%) A 6. Two particles with charges Q and -Q are fixed at the vertices of an equilateral triangle with sides of length a. If k = 1/411 ( o, the work required to move a particle with a charge q from the other vertex to the center of the line joining the fixed charges is: 00 Wake mun L in Seaé. \‘sm; '3' P” a“ = . ch‘vak Muv‘ m“ +0. -------------- "1 .5 ---------- ". —Q ?V;\,MV\;{;. Q :3 ~Au= o=H 0 Stem”! we“; qu/a U. _. - “’3 \‘G Q. Li; : __ \LQ Q c)qu/a2 *Ewfi‘": “673*? D) 2qu/a , t’ “69‘ E) ‘Zqu/a ' - kQ/C‘ I /6~ Us; '44: =‘> AUEUag‘UF-O :5 \Qr—O s‘mu NDIAU Q 7. For two different transparent media A and B, the indices of refraction are given by: M = 1.7 and m; = 1.4. Total internal reflection at an interface between these media: A) always occurs whenever the light goes from A to B B always occurs whenever the light goes from B to A may occur when the light goes from A to B may occur when the light goes from B to A m EM E) can never occur at this interface A ‘3 gr ketcA Lnuwud {exugfim to ocmnr hawk MN“; be mark." *wm «widow «431k Kg...“- n t» «Mic» 0-} W «xm‘ «Lats not gum-3mm tknt. totm‘mw M\ *eflus‘fim wi‘~\ CNN. 1-: may: «Ba, \34- tku’g Qmflhnt >92! Page 3 E 8. An object is 10 cm in front of a concave mirror of radius 40 cm. lts image is: A) real and 20 cm in front of the mirror c°“\°°~"¢ *3 *‘3 ° 5;: '7; ‘20s“ '? = ‘0‘“ B) real and 30 cm in front of the mirror r "em \ _‘ l . \ . . C) virtual and 30 cm in front ofthe mirror '35—); : ~3- 7); a {5 => 4: -Zoc.m «inward D real and 30 m behind the mirror virtual and 20 cm behind the mirror ‘7 'mgfme I ‘\ that.“ :‘r 'wmu‘z \oeM‘MA <7 9. A point par1icle with mass m and positve charge q is initially moving with constant velocity in the +x direction with kinetic energy K0. Then it enters a region where a uniform electric field of magnitude E points in the -x direction. What is the kinetic energy of the particle after it has travelled a distance d (in the +x direction) in the electric field region? 7-; g ; _ E: w: A! _._ K ‘4‘ A) Ko/d 6—— _ 1 B) qu/m +39 F375— “ FA 7% C K0+ A c __ :. @Ko— qu " H ‘~ 3 none of these .1) y": \Lo- 2631 C 10. In a Young's double-slit experiment the center of a bright fringe occurs wherever the light from the two slits travels a distance that differs by which of these sequences (where 7» is the wavelength of the light)? A) l). 21 2). 1,1 MGJGMB-i dSwS-zmk 4 ,4 ,4 ,4 , . ‘ h c\S‘in& 3‘5 k‘q $s§gfiuu so moyan B) 1,1,31,31,11,... \3“ 3 3 3 3 occur Jim, @ 1,21,31,41,... A x 5 > A} r L ‘ I ; ' v - D) 12,32,32,12,... ' 2 2 2 2 E) none of the above 6 ll. Monochromatic light is normally incident on a diffraction grating that is 1.6 cm wide and has 20,000 slits. The first order line is deviated at a 30° angle with respect to the direction of the incoming light. What is the wavelength of the incident light? A) A‘sstomu. .‘w M s\H-. 95....“ Una-bk - Levi-5‘“ nm ~ - - . u C) 500nm $1 9'=-Sc‘ mam-rm W. 1954*“ 1.0,ooo a; a :V —~_ '4 3 335?]. T] ““e‘w 5““ Wk : \ :wmgnemmu. \ : 4X‘D.;H_‘- 4009‘” Page 4 E 12. The separation of white light into colors by a prism is associated with: A) total internal reflection ‘ B) partial reflection from each surface C) selective absorption of various colors D) a decrease in the frequency of the light in the glass @ variation of index of refraction with wavelength y 13. Charge Q is distributed uniformly throughout an insulating sphere. The net electric flux in N - mz/C through the outer surface of the sphere is: 3; 33130 Ewss‘ Lewd, Nun gag: Rs-m'mh C) 2Q“: emu-ts W throux’k b. Q.\osg& guacth w 5 {5 m 9w E) 0 u‘k‘ku 5°“ ls Q/E'_ 6 14. A charge of 5 C is placed on a spherical conducting shell. The shell has inner radius of 5 cm and outer radius of 7 cm, and is hollow inside. A point particle with a charge of +2 C is placed at the center of the cavity. The net charge on the inner surface of the 51161133 m *zc. Mug. "befits. m QAv‘flu; MAM“; no.an A) —5C M o‘vkos‘filt “at, 0% vzc, “M‘wuq- Sufis‘kw ® ‘ZC 6.} tw. wtbfi. ‘ C) 0c D) +3C E) +7C “C Page 5 15. Light is incident from air onto a pair of transparent slabs, as shown, at a 30°angle of 6 incidence. What is the angle (with respect to the normal) at which the light exits the second slab? Shaw; Law his“! s:M{9.=V‘I$KVMB\ n‘s'w S“ = n‘su‘nG‘ Hz S :M Q!- : nmranSk‘v A 25° 30° C) 35° D) 40° E) none of the above z? 16. A 100 N/C electric field is in the negative x direction. The force on a proton (charge +e) in this field is: A) 100 N in the positive x direction E = - [o ON/c Z B) lOONin the negativexdirection Z; I, (“Home 1.6 x 10"7 N, in the negative 1 direction c 1.6 x 10'" N, in the positive x direction 3; o a ’d = F=gc = - /.bx/D"‘A/£ Page 6 ...
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This note was uploaded on 09/13/2008 for the course PHY 317L taught by Professor Ritchie/lang during the Spring '08 term at University of Texas at Austin.

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Exam1_59955_sol - Name: PHY 3l7L February, 22, 2007...

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