Physics 102 Exam 2 Spring Last Name: First Name Network-ID

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1 Physics Exam Sprig 4 Last Name: First Name Network-ID Discussio Sectio: Discussio TA Name: This is a opportuity to improve your scaled score for hour exam. You must tur it i durig lecture o Wedesday April 6 th. All work must be your ow, but you may cosult others i preparig your solutio.. You must both circle the correct aswer ad show your work. Full credit will be give for the correct aswer beig circled, ad a clear solutio/explaatio for how you got that aswer. No partial credit will be awarde Each problem cotais a short statemet of what work should be icluded, ad the first page is completed as a exampl All work must be clearly legible o the exam paper give (o extra pages may be attached).. Your scaled score will be the average of the uscaled score you received o the actual exam, ad the score you receive o this opportuity to redo the exam. Takig this redo caot lower your scaled scor 3. Oly a subset (approximately ) of the questios you submit will be grade Your score will be the average of your score o the graded questios. Each graded problem will cout equally towards your score, sice you must show your work for all questios. For example, if questios are graded o your exam, ad 8 have the correct aswer ad a clear solutio, your score o this exam would be 8%. If your raw score o the origial exam was 6%, the your scaled score for hour exam would be 7%. 4. Our goal is to have the results for this regraded exam available i the gradebook by readig day. 5. Good Luck! of pages (5 problems)

2 PHYS Exams Hour Exam (A) The ext three questios pertai to the situatio described below. A egatively-charged particle, movig at a speed v = 65 m/s, eters a regio of width d =.87 m that cotais a uiform magetic field of magitude B =.7 T poitig out of the page, as show i the figur The mass ad the magitude of the charge of the particle are ukow. ) I which directio will the particle be deflected? Up Dow ) What is the miimum mass-to-charge ratio ( m/q ) such that the particle ca traverse the whole shaded regio ad exit through the right? m/q =.64 kg/c m/q =. kg/c m/q =.47 kg/c m/q =.345 kg/c m/q =.896 kg/c 3) Now a electric field of magitude E = 78 N/C is added to the shaded regio. What should the speed of the particle be such that it travels i a straight lie across the shaded regio? v = 39.9 m/s v =. m/s v = 45.9 m/s v = 76.6 m/s v = 4.3 m/s

3 The ext two questios pertai to the situatio described below. A rectagular loop of area A =.45 m ad carryig a curret I = 3.9 A is exposed to a uiform magetic field of magitude B = 4.6 T, as show i the figur 4) What is the magitude of the torque exerted o the loop?.36 Nm.53 Nm.48 Nm 5) As see from the frot, i which directio will the loop rotate? Clockwise Couterclockwise

4 3 The ext two questios pertai to the situatio described below. Three log, straight wires, each carryig a curret I = 4.8 A, are arraged as show i the figure, with d = m ad θ = 3 degrees. 6) What is the magitude of the total magetic field at the origi, B total, due to the three wires? B total =.7-6 T B total =.7-6 T B total =.9-6 T B total =.36-6 T B total =.47-6 T 7) What is the x compoet of the et force o oe meter of the top wire due to the other two wires? F x = N F x = N F x = N F x =.3-6 N F x = N

5 4 The ext two questios pertai to the situatio described below. A coil of wire turs betwee the poles of a permaet maget as show i the diagram. The coil has N=34 turs of wir The maget produces a costat field of magitude B =.9 T. The coil has a cross-sectioal area A =.4 m. 8) The coil is drive at a agular frequecy ω = 4.8 rad/s. What is the peak emf, ε, this geerator ca produce? ε =. ε = 5.7 ε = 6.5 ε =.678 ε =.66 9) If the coil is drive i the couter-clockwise directio, i what directio is the iduced field at the istat show? The iduced field is directed toward the left. The iduced field is directed toward the right. There is o iduced fiel

6 5 The ext three questios pertai to the situatio described below. The series LRC circuit is drive by a voltage geerator with (t) = si(6t) olts. The remaiig circuit elemets have the followig values; R =.5, C = F ad L =.5 H. ) The voltage across the geerator the curret through the geerator. lags leads is i phase with ) Which of the followig circuit elemets has the largest peak voltage across it? Resistor Geerator Capacitor ) What is the average power delivered by the geerator? P average = 3.3 W P average =.65 W P average =.33 W

7 6 The ext three questios pertai to the situatio described below. The series LRC circuit is drive by a voltage from the atea recievig a sigal at 95 MHz with peak voltage of.85 olts. The remaiig circuit elemets have the followig values; R = 3.8, L = -9 H ad the capacitace is adjustabl 3) What value of capacitace will provide the largest peak curret i the circuit? C =.74 - F C =.5 - F C = -9 F 4) Assumig the above capacitace, what is the peak value of the voltage across the iductor? L max =.57 L max =.85 L max =.6 5) If you are travelig toward the radio statio at 3 m/s the radio waves will be shifted to a slightly lower frequecy. lower wavelegth.

8 7 A ideal trasformer has 5 turs i the primary coil ad turs i the secodary coil. A 6Hz AC voltage source with RMS voltage of 8 is coected to the primary coil. A resistor is coected to the secodary coil as show i the figur 6) What is the average power dissipated i the resistor? 5.6 W.6 4 W 5. W 64 W 3. 4 W The ext three questios pertai to the situatio described below. The electric field for a plae electromagetic wave i vacuum s give by E = ( N/C)*si(-.6 m - z + t). 7) What is the frequecy of the wave? f = 6 5 Hz f =.8 8 Hz f =.86 7 Hz 8) What is the magitude of the magetic field oscillatio? B =.4 5 T B = 7-6 T B = T 9) I what directio does the wave propogate? +x -z +z

9 8 The ext two questios pertai to the situatio described below. A beam of upolarized light of itesity I travels i the positive z-directio ad is icidet from the left o a series of two liear polarizers as show. The trasmissio axis of the two polarizers make agles of = 54 degrees ad = degrees, respectively, with respect to the positive x-axis. The itesity of the beam immediately after the first polarizer is I = 4 W/m. ) What is the itesity of the icidet beam? I = 69 W / m I = 48 W / m I = 74 W / m ) What is the itesity of the beam immediately after the secod polarizer? I = 3. W / m I = 59.9 W / m I = 74 W / m

10 9 The ext four questios pertai to the situatio described below. ) I figure (a) above, a coil is produced by wrappig a copper wire aroud a cylider of iro. The iro cylider is fixed withi the wir Which of the followig statemets is true: Neither of thes The iro will behave like a maget if curret flows through the wir The wire will have a iduced curret if the iro is magetize 3) I figure (b) above, a magetic iro cylider moves through the coil i the directio show. Which of the followig statemets is true: The iduced curret flows right to left across the frot of the coil. The iduced curret flows left to right across the frot of the coil. There is o iduced curret. 4) I figure (b) the cylider moves through the coil for t = 3.95 s ad produces ε =.9. What is the magitude of the chage flux? Δ Φ =.94 T m Δ Φ =.35 T m Δ Φ =.3 T m Δ Φ =.47 T m Δ Φ =.57 T m 5) I figure (b) the coil has a diameter d =.4 m ad turs of wir The resistace per uit legth is 34.3 Ω/m. The emf is ε =.9. What is the magitude curret i the coil? I = 69 μa I = 844 μa I = 53.7 μa I = 347 μa I = 537 μa

11 Physics Formula Sheet SP4 Mechaics: x at x v t v v at E tot K. E. P. E. F ma v a c r p K. E. mv p mv W F Fd cosθ m Electrostatics: kq q F r kqq r E U E you W F q U W U kq Poit charge: E, q r kq r Capacitace: Q κε A C Parallel plate capacitor: C, Ed d Q U C Q C C P C C C C C Resistace: q L R I Physical resistace: R ρ I t A P I I R R S R R R R R C S R P Circuits: I i Iout t / τ t / τ q( t) q ( e ) q( t) q e t / τ I( t) I e τ RC Magetism: F qvb si θ μi B wire B sol μ I πr Iductio ad iductace: mv r F ILBsiθ τ NIAB si φ qb ε N t BAcosφ ε bar BLv εge εmax si ωt ωnabsi ωt ω πf N I L ε L Soleoid iductor: L μ A U L LI I t AC circuits ad trasformers:

12 Physics Formula Sheet SP4 rms max I I ( t), si( ωt) I Rsi( ωt) ω πf R C L R max max ( t) C, max si( ωt π ) Imax X C si( ωt π ) X C ωc ( t), si( ωt π ) I X si( ωt π ) X L ωl ge P I L max max L rms ( t), si( ωt φ) I Z si( ωt φ) rms ge max R, rms I rms ge, rms max cosφ max Z f R π ( X C ) L X LC p s ta φ I I X s p N N X R L p s C Electromagetic waves: c λ E cb f u E ε E u B B μ u f f I I cos θ c rms B u εerms Brms εerms S I uc μ μ Reflectio ad refractio: θr θ i siθ si θ d o d c v i f R f si θ c hi di m ho do θ dear M θ f Iterferece ad diffractio: Double slit iterferece: Sigle-slit diffractio: Circular aperture: Thi film: δ or ) ( d si θ mλ d si θ ( m ) λ m,, wsi θ mλ m, D si θ. λ film δ ( or ) t δ ( or ) δ m m m,, λ Quatum mechaics: E hf hc λ Blackbody radiatio: p x x T λ max 3 λ h p.898 m K Photoelectric effect: K. E. hf W h π Bohr atom: πr λ,,3 L mv r

13 Physics Formula Sheet SP4 4 mk e Z Z r (5.9 m) mke E (3.6e ) Z Z 7 (.97 m ) Z λ f i Quatum atom: L ( ) L z Nuclear physics ad radioactive decay: m 5 A Z N r (. m) A N t λn / 3 λt t T/ N( t) Ne N T E mc l.693 λ λ / Special relativity: t γ t Costats ad uit coversios: L L γ 9 γ v c g 9.8m / s e.6 C 9 7 ε 8.85 C / Nm k 8.99 Nm / C μ 4π T m / A 4πε 8 c 3 m / s h 6.66 J s hc 4 me ε μ 9 7 e.6 J m proto.67 kg 938 Me 34 3 m electro 9. kg 5ke SI Prefixes Power Prefix Symbol 9 giga G 6 mega M 3 kilo k 3 milli m 6 micro μ 9 ao pico p