PH222-Su10-Final-SolutionRD

PH222-Su10-Final-SolutionRD - Physics 222 Summer 2010 FINAL...

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Unformatted text preview: Physics 222, Summer 2010 FINAL EXAM Friday, August 6, 2010 Name (Printed): :2 Air zé/Oh’f Section Number: Recitation Instructor: INSTRUCTIONS: 1. This is a two hour exam consisting of 30 multiple-choice questions. Questions 101 through 130 are each worth 1 point. Questions 121 through 130 are based on your work done during the laboratory periods. However, you can answer these questions also by using physics information from the lectures. I will count all your correct answers for a total of up to 30 points. Use your previous bubble sheet answering questions # 101 through # 130 on the back of your bubble sheet from the first three exams. 2. Use a number 2 pencil when marking your bubble sheet. Do not use ink. Ask for a pencil if you did not bring one. Fill in the appropriate bubbie completely. If you need to change any entry, you must completely erase your previous entry. Also, circle your answer on the exam. 3. Carefully read each problem and its five possible answers before beginning to work on the problem. Select only one answer for each problem. Choose the answer that is closest to the correct one. 4. Before handing in your exam, be sure that your answers on your bubble sheet are what you intend them to be. You should copy down your answers on a piece of a scratch paper for comparison with the answer key to be posted later. 5. When you are finished with the exam, place all exams materials, including the bubble sheet, the exam itself, and scratch paper that you used for the exam, in your folder and return the folder. Enjoyed working with you this summer and wish you all the best in your future endeavors. ' Good Luck! -- Art Meyers A resis‘tancclcss LC circuit consists of a capacitor nod rm inductor, as drawn in figure 101 Whom rhe current flowing through on inducior changes. a voltage {emf} gets crooked in the inductor 1h310pp05es uh: Chung: in the worm. So‘ inductors have an "mania" with 1:st Io changes in currem. just Iikc masses how: inertia with rcsooct to changes in velocity. In an LC circuil, charge oscéliatcs back and foflh lumen the two capacitor plates. just like a pendulum’s position oscillolcs back and forth belwocn fire two ondpoénss of its swing. For instance. in figure 101 suppose tho bottom plate iniriaily carries negative ctr-ago Exosss elecu'ons flow of? me bottom plate. through the inductor, and onto the lop plate. 50. the. top piau: new carries the negative charge. 3111 than. 111:: negative charge "sloshes" back onto the bottom plan. In this manner, one: charge osciliales. At any given momom. the ant-rm! Stored in the capacitor is Us 9 % ._ . “here Q dogmas the no: charge on [he lop plate. ant! C denotes 1hr: capacitance. The energy stored in the inductor is UL I“ 1.12, where! osmotic-s the canon: through the, circuit. and L is a constant caiicd the inductance. Since the circuii is essentialiy rcsistznceless. no heat dissipates as amour osciliatcs back and fonh. .In this circuit C E 6.10 farads and L =10 harm's. (Ponds and hcnrys are both SI units.) initialiy. at time I '= 0. the bottom plan: has charge: - LG mofomos. and no cam-cm is flowing. 101. Which graph hes: Tcprcscnls the chargu: on L11: top plan: of the capacitor as a function of lime? C :Ftop pane I 2' t... m-«Eilirm- _= barium plum + ...__I g) g” ' g 0‘ E 0 firm: Figure 101 3 .5 C D. + H D 6.3 9-0 GD 3 0 . a I) , é um: -== mo: :4 a E II“: 1-!- E} None of m: above graphs mprcssm the charge in fire top plate of the capacitor as a funczion of time. 102. An ion of mass m and of charge +3 is in circular orbit around a fixed pomt charge Q, with chargc -8.0 pc. The radius of the orbit is 0.20 m, and the speed of the iou‘irl thc orbit is 1.2x10‘ mis. A uniform external magnetic field. perpendicular to tho plane of the orbit, is present. The magnetic force on the ion is equal to the electric force in magnitude and in dircction at all points of the orbit. In the figure. tho mass m of thc ion is closest to: A)6110““kg B)5x10““° kg 4110"“ kg v: e 8 @ 8x10 2‘ kg Net t‘01‘ce=_m— = 91123 + k = 2k (because F3 2 F ) 7x10 ‘26 kg r r‘ r" 5 2kg 2x9x10”x1.6><10""><8x1 ‘6 , 3m: gq:—-——-———-—fi 0 28X10=fikg r'v 0.2x(1.2)‘ The correct answer is option D)8><10'3h kg If an electron is accelerated through a potential of 300 V and then enters, from the left, a region with an electric field of 12.00 x 106 MC pointing down {see figure below): X X x X. Epm Pflfim). 103. What is the election speed leaving the accelerating potential? ‘[in m/s] A) 1.05 x 10 1“ ' B) 5.25 x 1013 5133 {fa/42¢” _ .L .. @ 10.27 x 105 j 0) 1.05 x 107 E) Need more information to solve the problem. 104. What magnetic field pointing into the paper will allow the electron to travel to the right without being deflected up or down? [See figure above] A) 0.937 T I , . B) 1.05 T ' 5%.; .5.- t t/ :5 X a/ [a Law; @1153 T J 0) Not enough information given in Problem #103. E) Impossible since fields are in the wrong direction for there to be no deflection. 105. You have a long solenoid which has 1500 turns in 20 cm with an AC current of 3.5 amps flowing through the coil. This coil has a diameter of 4 cm and a resistance of 25 ohms. What is the magnetic field inside the center of the solenoid? [ in Tesla] A) 6.60X10'3 B 03299 a .. " 0) 4.57x10'2 E) 1.549 106. If a coil 6f 300 turns with a diameter of 1.00 inch was placed in the above solenoid (assume B,ms = 10 x 10'cl T) what will be the Errns voltage reading on an AC voltmeter or on a digital scope (in volts) if the frequency = 5000 Hz? [in Volts] A ‘15 . - . (33)) 25 fee Has/«J fit} a; C) 21 ' J 0) 23.5 E) 30 107. Consider a series R1. circuit consisfiz‘lg ofa Murry. 3 Switch, an inductor and a resistor aii oonnoctcd in series. The switch is closed and the curl-em and the voting: doings with time are mcasurcd- noted and platted in graph #1 and graph #2. “Fire graphing persons forgot to Iabol the axes. A; a physicist, you will do this for them. These are graphs of con-em and voltage versus iimt. The correct axes lobeis are as follows: A C a E. Q Q A) time cur-rem Lime voltage 3) current time voltage rim: C) time voltage Kim: current @ voltage time canon! time E) Home of the abort wmbinalions. 108- In tho figure. an insulated wire is bent into a circular loop of radius 6.0 cm and has two long straight sections. The loop is in tho x-y plane. with the center at the origin. The slraight sections are parallel to the z-axis. The wire carries a current of 8 A The magmde of the magnetic field at the origin. in 111'. is clscst to: 6"- )80 " “if (3)110 Dl100 3:3,”: +3 _ ., =_'“~”,E_L«" ’} m E) 70 A "m 2.5: 29m ‘ ' 4Ex10'? x8; _ 43x10'7x8 : 2x6x10‘3 22r><6><1tr2 " : —84><10"‘k —26.7x10'“}' 3r 3 r: \l84" + 26.7? ><l(l'“ = 88M" 2» The closest answer is A) 90g? 109. An electron has the same de Broglie wavelength as an 800 nm photon. The speed of the electron is closest to: [in m/s] A) 600 B) 700 c 300 566, a f—fwfiy/flz «525' @3900 J E) 1000 110. An object 8 m high is located 125 m in front ofa concave mirror which has a focal length of 200 m. Which of the following set of positions, size, and character of the image is correct? Image Position fl Character of Image A) -500 m +32 m erect virtual @D -333 m +213 m erect virtual C) +333 m -21.3 m inverted real D) +500 m -32 m inverted real E) None of the above. We. ci' «24/ or" {jet-1’ 111. Determine the focal length of a converging lens which will project the image of a lamp magnified 4 diameters, upon a screen 10 m from the lamp (in m). A) 1.25 . 1-5 f {96’ A {érrfia/ fflijis C) 2.0 o) 2.5 E) Not enough information. 112. A narrow beam of light strikes a glass plate (n = 1.60) at an angle of 53° to the normal. If the plate is 20 mm thick, what will be the lateral displacement of the beam after it emerges from the plate (in mm)? A) 26.5 B 15.0 I f I q C; 11 5 5 (9t? 5 .’ //Z'(-[{3(/ ,. @D 9.0 E) Not enough information. 113. 114. 115. 116. Two identical beakers are filled to the same level, one filled with water (n = 1.361) and the other with mineral oil, (n = 1.47) they are both viewed from directly above. Which beaker appears to contain the greater depth of liquid? A) same depth 1 4 water depth greater ; Cg ff {fig/u. _/ faJLze/f C) mineral oil depth greater ’ V/ D) Not enough information. An amateur lens grinder wants to grind a converging lens of crown glass (n = 1.52) with the same curvature on both sides and a focal length of 25 cm. What radius of curvature must he grind on each face? [in cm] A) 13 B 25 62$ 26 0) 50 E) Not enough information. 5.66 {,3 Lugg/ The interference pattern of two identical slits separated by a distance d = 0.25 mm is observed on a screen at a distance of 1 in from the plane of the slits. The slits are illuminated by monochromatic light of wavelength 589.3 nm (sodium D) traveling perpendicular to the plane of the slits. Bright bands are observed on each side of the central maximum. Calculate the separation between adjacent bright bands (in mm). 891.08 B 2.36 C) 4.72 0) 5.30 E) None of the above. The headlights of a distant automobile are 1.4 m apart. if the diameter of the pupil of the eye is 3 mm, what is the maximum distance at which two headlights can be resolved? [in m] Consider the headlights as point sources of wavelength 500 mm. A) 2030 B) 5700 . C) 6100 g M f; //z{/{.p///"j"5 ® 6900 E) No enough information. 117. A grating having 15,000 lines per inch produces Spectra of a mercury arc. The green line of the mercury spectrum has a wavelength of 546.1 nm. What is the angular separation between the 1st order green line and the 2nd order green line? a) 18.8‘3 21.40 .. c) 40.20 5 ('56) ii D) 59.00 E) None ofthe above. 118. In an important experiment in 1927, a beam of electerons was scattered off a crystal of nickel. The intensity of the scattered beam varied with the angle of scattering, and the analysis of these results lead to the confirmation of A) the particle nature of light. B) the Bohr model of the atom. @the wave nature of light. D) the Rutherford model of the nucleus. E} the quantization of energy levels. for fairy, 119. You have a blackbody radiator with a maximum intensity at a wavelength of 414.3 nm, what is the Temperature of the blackbody radiator? {in Kelvin} A} 6000 B} 5500 .. , c 000 (6?:500 5 H”) a It E) Not enough information. 120. The work functions for potassium and cesium are 2.25 and 2.14 eV, respectively. Will the photoelectric effect occur for either or both of these elements with an incident light of wavelength 565 nm? A) neither cesium nor potassium @cesium only C) potassium only 0) both E) Not Enough information. z. a! ....- -L'MVZ:3V 1’?"- /U “ m [93. z 3’ 3 I]??- / f ‘ ""i " yam! “ Zfl/Iéx'xv c)/€-//XID 2% 4/: 26/144 W.— Z - '5 :‘w. «if: no.2? m5 M/s Q 9 ,5“ [2.00X/0‘ IV/c. ., i M / H “g *— _ "f '- 5; -z;x/o+ém/5 /fi‘-f /Uv* fl ” / I 6- ; lag 7" c; ’ #‘” I -——/4 Mgnm’ W 5”” z ‘22? (W) [[3 '9‘ “4/22 // V’ d ' " ‘ rim; / ii,“ 7%“; gflflm/NLL)XN— WK . a a _ * 5%; :(2/7—76) MW gfmsr x2 2 1- ' *3!) : zzryfmfla] f?” WH](§,E-— ) (/0 M0 / M? I‘M- IN- HZc m: Mew/o 31's“ :. 7/03,},5/5 (g. xxxo'WgMS/rvxxwam) Cir/£6 % 7% wee ’5 "’m i ii 2 J...“ w, . /2'\/W f!- ZWI’M‘ ._ :Ll‘jfl-‘f—i [44- 5 8 /'Z.\/ t” r__ f... E— *' /W|7 /M h:— 2/:3/M ’_ *fl :*333M 5 " ’3 /4——g'—-—~ I 55“ 5'-‘*—P / I? F Mm {Uc‘t’m m . :_-. ’Z kmfhj ; ‘ "'79 y 5 1"; I /0m {ES /5" — 7 ==—? 5;: 5" A narrow beam of light strikes a glass plate (:1 = 1.60} at an angle of 53° to the normal. If the plate is 20 mm thick, what will be the lateral displacement of the beam after it emerges from the plate? The situation is described by Fig. 34-15, with CE the lateral displacement; E: = 20 mm. sin 53° 1.60 E = 26.5 w 11.5 =15.0 sin r = r = 30n E = 20 tan 53° = 26.5 §E=20tan30°=115 EE=EBCOS 53° = 9.0 mm ® l/ 3.- //L/_‘ Two identical beakers, one filled with water (:1 = 1.361) and the other filled with mineral oil {n = 1.47), are viewed from directly above. Which beaker appears to contain the greater depth of liquid, and what is the ratio of the apparent depths? Figure indicates the bottom of a beaker by point P. For an observer looking in the —Y direction, the image of P, labeled P’, will be determined by a vertical ray 1 and the nearly vertical ray 3 {or 2). Since 9 and til2 are small, Snell’s law gives 1 n131==n232 or fl=3 92 “'1 But 25=ytan 61=y’tan 92 or tan law-01:); tan 6: 92 y Consequently, for given y and n2, y’ is inversely proportional to n . The water-filled beak by a factor of 1.47;1.361 = lbs. 1 er appears deepen - _(exaggerated scale] An amateur lens grinder wants to grind a converging lens of crown glass (:1 = 1.52) with the same curvature on both sides and a focal length of 25 cm. What radius of curvature must he grind on each face? Use the lensmaker’s equation. (C3 1 1 1 . }=(n ~1)(§—I—R—2) With R,=—R2 or 1 1 1 2 , . — = (1.52 — l)(— — —) = (0.52)(—) and R, = 25(0.52)(2) = 26 cm radius of curvature for each Side 25 R! _R‘J R! . The interference pattern of two identical slits separated by a distance d = 0.25 mm is observed on a screen at a distance of 1 m from the plane of the slits. The slits are illuminated by monochromatic light of wavelength 589.3 nm (sodium D) traveling perpendicular to the plane of the slits. Bright bands are observed on each side of the central maximum. Calculate the separation between adjacent bright bands. Us” Fig. m The situation is shown in Fig. 36-4. For the first bright bandm = 1. The path difference is one wavelength. -3 -10 5893xllil'm=@<—1r‘g—-z -5893X 10 =2.36X10'3m=2.36rnm O “1:3 1 3'" 0.25><10”3 separatism of adjacent bright fringes. The headlights of a distant automobile are 1.4 m apart. If the diameter of the pupil of the eye is 3 mm, what is the maximum distance at which the two headlights can be resolved? Consider the headlights as point sources of wavelength 500 nm. D :: gm} duffikcé I? a at. {$1 wig/yea] Using the Rayleigh criterion for resolution of two point sources Disen'ed through a circular aperture of radius 4‘ and the equation for diffraction by a circular opening, we have 1.225 x 10”) A minimum angle that can be resolved = 9 =: sin 9 = 1.22 2 = W = 2.03 x 10“ rad /. Then setting 6 = 1.4LflWe get 3: 1.4;‘8 =1.4{(2.U3 X 10“) = 6900 m. A grating having 15 000 lines per inch produces spectra of a mercury arc. The green line of the mercury ? spectrum has a wavelength of 54615:. What is the angular separation between the first-order green line and O the second-order green line? L_% 6"? 6, I I X / 9"“ 9m Use the grating formula and solve for 8 for both R = 1 and n = 2, with distances in meters: ml = d sin 8 5461 X 10—10 = Man 91 01' 0.3225 = sin 9] and 9; = 18.8° first order Next, form = 2, 1 . . o 2(5461 x 10—10) = sin 62 or 0.6449 = 5111 82 and (92 = 40.2 second order Finally 6: — 6. = 40. 2° — 18.8” = g1._4° separation. @ in an 1111130118111 experiment in 1927 a beam or electrons was scattered or! a masts! of [f 3 I nickel. The intensity of the scattered beam varied with 11m angle at scattering. and analysis if time results lead to eenfirmaricm of A) the particle nature of light. B the Bola model of the atom. C) the wave name afelecuum ) the Rutherford model of the nucleus. E) the quantization {if energy ie-vcls. 17?. I fly, glad/5% Mwéak—Zijm‘k /: 4/%3X/0'm /zfl. 2: (éfinm .._ :fli = IzL/WVWM r 2.2061/ [3‘18 2 S'JCMM 7 7jcesrah~ {W 54% M! {a S}?! at”, haiku [fl/wfieéafiic 42W (441/ War/h (’9’: VOéffrI/lm I PHYSICS 222 Summer 2010 - Laboratory Final Exam 121. When an electrophorus is charged according to the procedure explained in prelab and lab 222-2, the charge accumulated on the metal plate of the electrophorus comes from: a. The handle of the electrophorus b. The plastic plate that was rubbed before placing the metal plate on top of it. c. The air around the system. C]. The ground, Via the table under the plastic plate. (e) The ground, via your finger when you touch the metal plate. 122. The voltage across a resistor is measured to be 4.5 i 0.2 V and the current through it is found to be 1.2 ir 0.3 A. What is the range of acceptable values of the resistance that we can calculate from our data? Between 2.9 Q and 5.2 o. b. Between 2.9 Q and 4.3 Q. Between 3.1 Q and 4.8 Q. Between 3.3 Q and 4.8 Q. Between 3.3 Q and 4.3 Q. 99.0 123. Incandescent bulbs are an example of non-ohmic system. Which of the following graphs is the best representation of the current versus voltage graph for such a system? I I 124. The graph illustrates the decrease with time of an exponentially decaying voltage. Potential difference {'9'} What is the time constant of this decay? a. 4.1 s 5.6 s c. 7.2 s d. 9.4 s e. 125 125. 126. A laser beam strikes a semi-circular transparent block as shown below. The incoming beam is aligned with the 0° position and hits the block right at the center of the flat surface. Semicircular plexiglass block Laser beam 270° Polar graph paper Platform When the flat surface of the block is Oriented along the 100°-280° line, the refracted ray comes out at an angle of 182°. What is the index of refraction of block? 1.2 b. 1.5 c. 2.3 d. 2.9 e. 5.0 In the electron tube used in experiment 222—6 Electron beam in a magnetic field, electrons were produced in a hot filament, accelerated towards an anode, and sorne of them went through" a slit and into a glass tube placed between the coils of a Helmholtz pair that produced a magnetic field in the tube. To increase the number of electrons in the beam (i.e., to make the beam more intense), we should increaSe: 61:.) The current through the filament. The current through the anode. The current in the coils. The number of turns in the coils. None of the above, the intensity of the beam is fixed by the filament material only. 921.053" 12?. In experiment 222-8, the test coil in the figure below was placed inside the solenoid to observe the effects of magnetic induction. Oscilloscope 51 0 Test coil a. Function generator cut a ==-: J Solenoid (15 cm long} BNC cable Assume that for certain conditions, the oscilloscope produces the following graph: Ellflflml MI-‘Ilflflll‘u III-III...- III-III..- III-III..- If we keep all conditions the same but double the number of turns in the test coil, which ofthe following graphs is the closest to what the oscilloscope will read? I 1‘ I I E I I I 2 “II II III EIIIIHIH I‘IIII‘IIIII'I EIIIIILI'I I I I I n... ' I _ -—"'"' IEI-EL -_I!!EII fi 1 ‘ l Ill-Enllllna A digital AC voltmeter is connected to a function generator that produces a sinusoidal voltage with an amplitude of 5.0 V. What does the voltmeter read? When you hold a lens with focal length f = 5 cm at about 30 cm from your eye and look at an object through this lens (say, a lamp), what do you see? 128. ® C. d. C. 129. a. b. (‘3’ d. C. 130. An inverted, larger image of the lamp. An upright, larger image of the lamp. An inverted, smaller image ofthe lamp. An upright, smaller image of the lamp. Nothing, the image is completely blurred. When white light shines on a thin film of oil floating on a puddle of water, beautiful rainbow patterns appear. Why does this happen? a. b. @ d. e. Because different ratios of the amounts of oil and water mixed in different places produce a different reflection spectrum. Because different ratios of the amounts of oil and water mixed in different places produce a different absortion spectrum. Because different wavelengths produce constructive interference for different thicknesses ofthe oil film. Because different thicknesses of the oil film reSult in different indices of refraction. Because different wavelengths are reflected in different directions. ...
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This note was uploaded on 02/11/2012 for the course PHYSICS 222 taught by Professor Ogilvie during the Fall '05 term at Iowa State.

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PH222-Su10-Final-SolutionRD - Physics 222 Summer 2010 FINAL...

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