S09 - Exam 3 - solutions(1)

# S09 - Exam 3 - solutions(1) - Physics 116B — Spring 2009...

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Unformatted text preview: Physics 116B —- Spring 2009 — Exam #3A Name: Ki: 0 You have 90 minutes to complete the exam. 0 You may not leave the room after you start the exam. , 0 Only calculators, pens/ pencils, and your one—page formula sheet are allowed on your desk. No additional scrap paper. 0 All electronic devices (other than calculators) must be put away, and cell phones must be silenced (not set to vibrate). ' I pledge my honor that I have neither given nor received aid on this work. Scores: MC /24 #13 /10 #14 ﬁe Raw M4 MULTIPLE CHOICE. Choose the one response that best completes the statement or answers the question. Write your answer in the blank space at the right. (2 points each) 3 Q i 1. If the electric ﬁeld in a plane electromagnetic wave in vacuum is given by 1. E0 sin [(3x 106 m"1) m — wt], the vaiue ofwis: k; BAlOrnn/f‘ '2 2117* A 9 1014-d x 1a /s V: B) 9X1016rad/s ' I C) 10rad/s C : (Efﬁe) 42%: D) 0.01 rad/s W E) 100 rad/s m :C‘k : (3mogmls‘13ifd’d‘) 36km /s 2. An electromagnetic wave is transporting energy in the negative y direction. At one 2. g point and one instant the magnetic ﬁeld is in the positive a: direction. The electric ﬁeld i ' at that point and instant is: A) negative y direction :3 ex EX negative 2: direction C) positive y direction E 5 i D) negative :1: direction W E) positive 2 direction ' ’5 J/g / E E X 3. A sinusoidal electromagnetic wave with an electric ﬁeld amplitude of 100 V/m is incident 3. . normally on a Surface with an area of 1 cm2 and is completely absorbed. 'The energy absorbed in 105 is: A) 27mJ U is? at“ W B) 130mJ V 1 W m w i a 41 (,2- gm at)” ‘5" )3-3 "12 13:12 £550 ,2. m; gm :Z/(ggsxlo MWﬂEA/D {le m) _ i . m E) 270mJ LL“: ¥lecm§fﬂ9§> i: T i 4. The diagram shows the passage of a ray of light from the air into a substance X. The 4. index of refraction of X is: A) 2.2 B) 0.53 m I 9.; l (s C) 3'0 am He" n.3, smzlo D) 0.88 ‘ L ’42.? E‘Wm h? a: [.5787 1-9 siege“ 5. The illustration shows total internal reﬂection taking place in a piece of glass. The 5. 0 index of refraction of this glass: to": 9,; .sm to" 2. 5m 9.; == any.“ A) is at most 2.0 B) is at most 1.15 C) is at least 2.0 El is at least 1.15 E) cannot be calculated from the data given WW\ \}0 A) real erect, and the same size as you r‘n Crm'l’" 99” a, Pleat Ml‘rror, yaw!“ Damage. ['35 ,- , r wmimrmmsamagsas: 6. C... B) real, erect, and smaller than you virtual, erect, and the same size as you - D) virtual, erect, and smaller than you T E) real, inverted, and the same size as you Mme» WWW 7. A point source is to be used with a concave mirror to produce a beam of parallel light 7. D rays. The source should be placed: A) at the center of curvature B) midway between the focal point and the mirror C) as close to the mirror as possible IE midway between the center of curvature and the mirror 3: Ar)” china» 65*“ Pam‘f“ E) midway between the center of curvature and the focal point 8. In a cinema, a picture 2.5 cm wide on the film is projected by a single lens to an image 8. E 3.0m wide on a screen that is 18m away. The focal length of the lens is about: A) 20cm Lane“; «HM; (Meg; is I‘Amrimf £13454. 5+“ e‘s Fast) I 15cm M: 39; «3m :1 fem 0) 100m E) 2.5m s D) 7 5cm 3.; v 155 M E) 12.5cm l ‘ up L‘s-5"“; amigLa-s \ ml at, 9. Waves from two slits are in phase at the slits and travel to a distant screen to produce 9. the third side maximum of the interference pattern (third from the central maximum). The difference in the distance traveled by the waves is: A) a wavelength B)Zwavelengths C) three halves of a wavelength D) half a wavelength three wavelengths ' ‘ , \\ ,1} gr»; 2A M”; W? a W U? 10. One of the two slits in a double—slit experiment is painted over so that it transmits only 10. E one-half the intensity of the other slit. As a result: A) the fringe system disappears B) all fringes get dimmer C) the dark fringes just get brighter D) the bright fringes get brighter and the dark ones get darker the dark fringes get brighter and the bright fringes get darker ‘ LML‘M H’k’ 'Kﬂl’mé'h/ fmm "‘“fr {are a pastel)", bf‘tﬁiﬂt fritwé‘ 221:4 is. realucaal b») ih) A“ PM 5339}? callerhw ems) 9151’) "QWVAQ no lodge-r .gxoaiwc, \$3353." lﬁh u: E (mfg? €an§frwr3nw 93L” Wéa‘lri‘wwiuag m hangarcmw, Lad/l4 M3114“ \$0M W.CiLM{§li+r 11. rI‘hree experiments involving a thin ﬁlm (in the air) are shown below. If t denotes the ﬁlm thickness and A denotes the wavelength of the light in the ﬁlm, which experiments will produce constructive interference as seen by the observer? The incident light is nearly normal to the surface. Hints: (1) Yon don’t need to know the index of refraction for the ﬁlm. (2) Total energy has to be conserved, so more reﬂected light means less transmitted light, and nice verso. incident light incident light . incident light eye eye o o o I u u o u n o n v v o a I II a u I I a o u n o v v n a I I. c u a u u u u o n o o v o o I I II a o n I a o u o o o n o o I ll u o o I I u u I o n n n I I I I II c o a n a u .9 u u n u I a o I. o o I I c o o o o o v I I o n o o o o I I c o v o o a u I I c o o I I II III M {fetal/k Ease} I"? Lee.- leolé gi" aller COMl'nj A) Ionly [ B} 11 and 111 only 4°?) “HAM Mil 5" 5M” twat twill“ IMERE‘Y'éiaav-ig C) II only v» w m ﬂ “L z I D) HI only :3 23*? 5" l; m (it 23%. law A 2“ i >\ % (KM however} W- We inﬂict/1:) airam «like inelij 45¢: .5 t'lr‘Lka‘l'L'éa/‘l :5 Fﬁuifgegl, 12. Light of wavelength A is normally incident on a diffraction grating G. On the screen 5, 12- E3“ the central line is at P and the ﬁrst-order line is at Q, as shown. The distance between adjacent slits on the grating is: incident light a i l l l i . | 1 FREE RESPONSE. Write your answers in the boxes provided, using the units given. You may receive partial credit for work that is shown clear-1y. (18 points each) 13. Unpolarized light with intensity Io is incident on a stack of three polarizing ﬁlters. rI‘he ﬁrst and last ﬁlter have their axes parallel to one another, while the middle ﬁlter is rotated by 30 ° with respect to the other two. (A) What fraction of the incident intensity I0 is transmitted by the ﬁrst ﬁlter? lam {rider/i ﬂaunt” qiwét.)5 lets «was 3 use tbs, “This ‘15 sci” ngingE Lara I/Io = ‘ /1 (2) (B) What fraction of the incident intensity is transmitted by the second ﬁlter? “m Was its as ﬁrst it“ <3) rs 3iW bi, Malta's Lee I, r: ‘IMAK 33:3? 6% (C) What fraction of the incident intensity is transmitted by the third ﬁlter? w 9‘36: Lark“? gab '5; tetra/“hiss; «is th’l “Di if” “Jeremy; 6’s} 5; 3g . . "P ,r ,L, ‘2“? g (D i" {a it @5059“ 3 Wk “ J” at; s are (D) If the middle ﬁlter is removed, what fraction of the incident intensity is transmitted by the third ﬁlter? . - I; Lt>1\$f‘l/\_€§az\f\w 41w: Wir‘sie’iEé‘é- ‘9' Hm I “M” Mo = i, (2) “swat grime ne‘iﬁ‘ﬁ; l L (efﬁgéi‘é) Tarp 2-: "i 6 14. An object of height 5 cm is placed 1 In to the left of a diverging lens of focal length f1 = —1 In. A converging lens with focal length f2 = +0.5 m is located 1 m to the right of the ﬁrst lens. For the ﬁnal image formed by the pair of lenses, answer the following: (A) What is its location relative to the original object? (B) Is it real or virtual? (1) 52} > 0 }50 (tall (C) Is it upright or inverted: (1) 3 55¢? (nursed!!th f; (D) What is its height? MGM-‘35:“- :ﬁ'ligmw ML h: l-25 cm (4) \$\ “ \m h 5 j: ok on" -3» mzm '3 gains 2 33294 Z \si mamméa “1% ...
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S09 - Exam 3 - solutions(1) - Physics 116B — Spring 2009...

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