opticsexam2 practice key

7/27/2019 OpticsExam2 Practice Key

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Pro..e-tic ... ~ f 6 iHYS 3190,_-_----., Name:Dr. John Soh1 ]jus. I fs 81 7 r '. No Ime LimIt, Score:__ (/50)Math tables, calculator, ruler, 8.5 X 11 note sheet allowed. Instructions: You MUST show all work to get full credit, if ! can't read it I'll assume that it is wrong. Circle your final answer. By affixing your name to this exam you certify that you have not and will not talk to anyone about the exam prior to the "Due date." If you need more space, use the back of the sheet and make a note on the front to direct me there. EO = 8.8542 X 10- 12 C2 N- 1 m- 2, !-Lo = 4n X 10-7 kg m A 2 S-2, C = 3 X 108 mis, h = 6.626 X 10-34 J s1. (10 pts) Light of continuously variable wavelength illuminates normally a thin oil (index of 1.30) film on a glass surface (nglass =1.50). Extinction of the reflected light is observed to occur at wavelengths of525 and 675 nm in the visible spectrum. Determinethe thickness of the oil film and the orders of the interference.

. . (J.es7l).c (IyYll r l /Mt . . . .v . I V\+e . . ( ' e J " ~ II.J = t6f t- ~ r________-L___________ * =2.",* + 0

," .

(J'7

~ , + - ~ ) - I \ == ~ ,

.. . - - - - - - ~//


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O ~ + j c > l< ~ ' {2. (4 pts) When one mirror of a Michelson interferometer is translated by 0.0114 em, 523 fringes are observed to pass thecrosshairs of the viewing telescope. Calculate the wavelength of the light.

~ b /\)== LJ(:(.,;) ~ L : l J . . .

3. (6 pts) The plates of a Fabry-Perot interferometer have a reflectance coefficient of r = 0.99. Calculate the minimum (a)resolving power and (b) plate separation that will accomplish the resolution of the two components of the H-alpha doublet of thehydrogen spectrum whose separation is 9.472 GHz at 6563 A.

I.

u . s ~ ~ ~ ~A A A : : ~ . d ) )))

=- ~ A'Vc.....,

5: 0 Ive - G ~ y0.. ..a.. '13 J.S",- ~ 30 Cj1T v1100

" \ J i l 1 ~ , t L i ~ ,; j Ik\ -J =- 1i [F(ll">..) ."'" ',",


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. O ! J ~ \ C ~ K ~ Y7. (10 pts) The larrel-Ash 0.25-meter spectrograph in the lab provides a i'runimum of 0.2 A first order resolution anywhere inthe visible ~ p e c t r u m ( ~ O O to 700 nm). The ruled widt.h of the grating is 5.0 cm. \ . ._(a) Determme the mmmmm number of grooves reqUIred. . IN'l - I

yr ' \ NR=: -


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36

(;+i(7 K,;Y Bonus Problem (6 points) An echelle grating is ruled over 12 cm of width witt 8 grooves/rnm and is blazed at 63.Determine for a Littrow configuration the following:(a) The range of orders in which the visible spectrum (400 to 700 nm) appears. L ' / n..L.. IJ \J;fh 0.... ? ~ ,-,co,Jirr'J see p""ev1 ee-vte(i '- tjrtJ.fitfd is u.se#.. u ~ . ( ' i x . ~ d ' - - o . ~ J e . "A

:Crt LiHrow VlAOIJ. ..+ /0"'- ~ f{.e b t j ~ ~ t ~ s + - r e s f , , ; 1 S ~ ; ~ your; r'ltiJevlf /;jI! YI or ""'/II< I to 1"'- e hI ~ . : r e Sv r..(t&.ce J ;,e. J (; ; ==- eB -:::: 61"'f\"\ A=: fA ( ~ , . t'I (9 f $. ill! (/J) ==- .z

opticsexam2 practice key

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