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h133_1094_2_key

# h133_1094_2_key - H133 1094 Session 2 Write your name and...

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Unformatted text preview: H133: 1094 Session 2 Write your name and answers on this sheet and hand it in at ﬁre and. There are a variety of activities today; watch the time and try to get through them all. Work with others at your table on these activities. Argue about the answers but work efﬁciently! After the indicated time, move on to the next activity! 1. QB: The Photoelectric Effect [20 min.] Start "up the PhET applet "The Photoelectric Effect" (Start~>Programs->PhET, choose "Quantum Phenttmena" from the left menu, and click once on the Photoelectric icon). The simulation shows light with a well-deﬁned wavelength and intensity (which you control), incident on a metal plate (cathode), which causes the emission of electrons (depicted as little balls). The electrons can travel (if they have enough energy) to another plate (anode), completing an electric circuit. You can apply a voltage and measure the current. a. Increase the intensity so that electrons flow. Sketch here your prediction for what a graph of the current vs. the light intensity would look like. Then select the "Current vs light intensity graph" and move the intensity through its entire range. Fix your graph as needed. Is this result consistent with the wave model or particle model of light, or both? Explain. m cornea)? Siomhti he iiwi meDCmth mt wit: / (ﬁg mcjﬂ ._ @WHQ h c Sat. OWE tam ’§)b\l\4§ with its. an Sims so some he Comm)“ . Th re, \3 teasiéh'ﬁi ------- -;_--_ ----------- \sitvw “e933 N Nutrer RN}- Qﬂ‘de Wade‘s . twin-him} ' b. Set the intensity halfway. Adjust the voltage to make the electrons just stop, so the current drops to zero (this is called the stopping voltage). Why is the polarity of the voltage such that the anode is negative? How is the stopping voltage related to the maximum kinetic energy of the electrons? You can _ read off the wavelength of the light and the stopping voltage. Calculate the work function for sodium (and give an appropriate number of signiﬁcant figures). * cit-yobs). is i Soﬁa? \i Kafka €15 5-5 ore cytjmtﬁnupimh‘: «again/e. éiopgimyvciiagﬂ‘iims ‘1 \6 Tie maximum K8 in 9V5 . .. V/Vhwiﬁm; MTWQJ \ig-bp'f'wbﬂb . 90 km": (31% a}! I Km Sgniwni * :- hs.“ as c. “C —‘ : WOW‘M :. y< ,\ is N X— (W W -mew saw (9,)th may c. Note that the initial target is Sodium. Devise a way using the "Electron energy vs light frequency graph” to rank the work functions of all the possible targets from lowest to highest. Try it out. Explain what you did and give your result. (Hint: Move the wavelength through its entire ran e.) ash“: / m 'lﬁgﬂi is “Pk Shaw ﬁltv Win“- i‘NQ‘T-H )SD “psi ﬁre U? WK / ‘ \oméji‘ Alt) \fgﬁl‘cqﬁf E "resins, tin < Ca < Zn < Cod 6% ‘ “‘9 ‘ so? was not 9.1.0 ate 2. Q4: The Wave Nature of Matter [15 min.] Start up the PhET applet "Quantum Wave Interference". This applets simulates wave phenomena from both light (photons) and particles (electrons, neutrons, helium atoms). a. Turn on the light gun and then (on the right) click on the "Double Slits". Look at the pattern on the screen. Predict below (qualitatively) how it will change when you change the slit separation, then test your pregivction with the "Slit Separation" slider. CE‘LL \anu 1am-onm Mg, \uw' and x oat-k s Mass .201 hex deck Q‘ﬁpeo 05C him A ssan 5 ‘13} 5? at a». 5,51 g I Sb anaacgiwjﬁ \$\\\‘ A W“ MACE Q} S‘mimgi‘ , Mn mg m Mﬁ?{9£sWL\O\$(¢QY0mc-Q(Mt (5.0L. b. New switch from photons to electrons (using the pulldown menu above the Gun Controls). Explain the pattern you see now. Predict what will happen to the pattern when you decrease the electron velocity to 700 kin/s and then test our prediction. \ QQM ﬁve at iﬂo‘éf‘inm WWW“ ~ Hamster) “he who)? N\\\ tmmgg, “eu— Mvnm‘ﬁ increase. (23 3Se the. Mic €01ch mots c\ v, c. Do problem Q4B.2. (Hints: Follow Example Q4.1. 1 keV = 1000 eV.) What will happen if a beam of such electr ns passes through a 0.01 nm slit? 0% V {Kris : ‘33” am : 0.6mm @Wdttsnpwm . , was be at as sin, a tum at 5M oar m‘rmlg 59am itltmd'xm. d. Look at problem Q4R.2 (but don't solve it). What is the effect of making h much larger than in our ' ? Wh ar th 1 t stand wher ‘t be hit b bats? ‘ universe y e ere p egg—s” e you won (Shakth mo?“ ‘0 \‘l P WW ‘5 530‘?“ thsc fr, (9531 5 am broom “ ‘ ﬁlm \Ji“ ymhﬁ u.ve it‘hﬂcgiamom Ui- ﬁt bu’tﬁ )50 Law (an “brawl ‘0 i _ 1 (ti v ﬂeet; . 3. Group Problems [10 min.] I w I. i‘hmmir] a. Why do radio waves diffract around buildings although light waves do not? Kathe armour/w), 5 are messiah lg“ loads?) No thmﬁs slow \i ‘ﬁl (While) Wumumjfwg 0st. WW) “Main S'WNU‘ ,9o no do ratiﬁes 15 mega, Q Centerofscreen Top view (not to scale) P him 9x b. The photograph shows the pattern on a screen from a distant source of red light that passes through two very narrow slits. Point P is the center, which is bright, and Q is another bright region. Point R marks a minimum of intensity. 0 Find the path difference in terms of the wavelength lambda for each of the points P, , R. Q L [above tic) Q: Q1 /\ (use S‘YWtiV‘VO O The distance from P to R is 1.6 mm and the screen is 2.2 m from the slits. What is the slit separation? was“ We gang 4; wﬁ‘n Xwﬂrwnm (“3) i, i- amt/g m ________ __ ‘1 was“) ._,W... m c. Give two reasons why the usefulness of large telescopes increasea‘as we increase the lens di meter. ° ESE 0i (Cit lib-r3 “:3 vesohﬁlnn be but 3w“ Goggle;- ggm rm , s mamas/0 \xo‘ﬁf Co‘Qd—‘ioﬁ 2% am data-3’ drmrwﬁ“ \$003 ,, ...
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