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quiz_1_solu - ME/ECE 141A Winter 2009...

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Unformatted text preview: ME/ECE 141A, Winter 2009 NamengjzgllflQflémmm Exam 1 January 2181:, 2009 NOTE: Show ALL work. STATE ali assumptions. You can use the back and front of the pages as necessary. Multiple Choice Questions / Short Answers - 4 Problems, 25 pts total 1. A baseball is made of trillions of triilions of atoms (it) Write out the number for one trillion trillion \000 000 000 00C) 000 000 me 000 10 (b) NASA estimates that there are about 1021 stars in the universe. Is this number higher or iower than the number of atoms in a besebeli‘? m are We )ooo Jnmes em sla tr: 2. or False? The smallest spot size we can illuminate with a given lens depends on the wavelength of light we use. 3. Which of the foilowing iists of sublevels is given in ascending energy level? (a) 35, 3p, 3d, 45 (b) 1s, 2s, 35, 3p (0) 2p, 3s, 3p, 4s (d) 3p, 3d, 48, 4p 4. True or Feise‘? Atoms typically absorb light at all of the same wavelengths they emit light. Jll’l'e Muelfmfl’lbi dose/heel 5m? 0i \ Bobs-st 06 “no 36 gmiflgal 3 Long Answers - 3 Problems, 25 pts each 1. Microwave Thermal Imaging. We talked about infrared thermal imaging in class, more specifically, how measuring intensity of a certain wavelength of infrared light can give us an accurate temperature profile. Here, we are interested in using microwaves for thermal imaging instead. (a) If we were to use microwaves for thermal imaging what is the temperature range that I would be able to measure? (b) Is this a feasible method for general temperature profile? Why or why not? ® MxemwaveS: beheem id'le ti fl_m oases 3x10” ‘2 m-K x a 0.18%?) mag mov: SO ® “lla’v’fra MeWoA ‘3 NOT Qaasdow became rl 03“ Owl‘j MQQSUVW EXTKEM ELY \O-u) ‘lempe wbwb \s “of Poached: ml’Uurf’S 2. Sodium Photons. The Sodium atom has 11 electrons. It has a mess of 23 emu and an atomic diameter of 360 picometers. We will look at the wavelength of photons emitted by the Sodium atom by making the approximation that this atom is similar to a onewdimensional, infinitely deep square well. (a) What wavelength of light does a photon have if it is emitted when an electron jumps from the 10th energy level to the lowest energy level in the valence band of en Na atom? (30) Now that the Ne atom is at its lowest energy state, what is the least amount of energy required to put in so that it emits visible light, and what energy level does this correspond to? Kr' lounge enema ‘1 ’2. ' Y :: lsz 231.12" 3:5;i level tibia ® l\m NOR (3 . ‘3‘“? h : t.t2.6x10"3q 33% “a ‘ '1 m. : O Xlo m AE 2 Ml \(nxo "‘ QL # BMW“ 36; TRON genng ma : mass (g cm ELEC 0mm x163" W} Li \m (3 s 3X\03 m/s 7- 1'1? 3. Wind Turbine Scaling. Clipper Windpower in Carpinteria, CA is currently devel— oping a 10 MW Turbine Engine, and the tip to tip diameter of the blades is 150 Hi. Does is make sense to try to fabricate wind turbines at the nanoscaie? Please make sure to mention the following: (a) How much more or less power will nanoscale turbines generate? (b (e ( d What are the practical considerations involved here? How much more or less force from wind will be available at the nanoscale? ) ) How much more or iess material wiil be needed at the nanoscale? ) ) (e Does is make sense to try to fabricate wind turbines at the nanoscaie? @ 90W 6 C“ Sale?) Q5 ’02 A? mm WWW?» will preciuce if)“3 as (eagles-5rer VISCODS eECecis, eh. .‘) mUCln powe v" D J a K _L totem" befiSilg Eagles (13 D K denSILj ' a mm‘lurbxm will have (0“ higher Power“ L viscous agree )5 “if: gag/i '1 0”“ as MUG/’1 (O) ’POCCC SCQlfS a3 D exgggflé'k’mtoj‘ I I ca 3 Qeme - \3 W15 (New Pmchccw? Haw 01963 44/113 5 WW (anemia Wermei when? G) \I’OlUWléi N D?) So eaflln ‘iTFlON/‘e .: {small Q5 maxi/I maimed volume (on lot: 5”“ r WWW) lo WW Same (1%) deeemolmj on POW/(AUG?) (aniOLBl’) WED?) bfi l-€33/ifi®{€ COB \A/Hvd mam helluva 0L mmsm (k WWSHj mom oileciecl )» weed ggfiemk/(J C H WNW-A meamg {\O’H’m/fl (4.918 {5 e: a: 1L) Camnoi’ be ...
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