CHM 424 EXAM 2 - COVER PAGE FALL

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1 CHM 44 EXAM - COVER PAGE FALL 006 There are seven numbered pages with five questions. Answer the questions on the exam. Exams done in ink are eligible for regrade, those done in pencil will not be regraded. coulomb = charges amp = coulomb per second volt = joule per coulomb ε 0 = C J - m - h = J s k = J K - c = m s - amu = kg in =.54 cm c n = v E = hν = ( nl ) f Rin R out ( n n) ( n + n ) dim = + R = M = f d d d ob im ob ( )( ) ( )( ) * ( η ) +η σ * + + ( +η ) +ησ n n n n n R = = n n n n n n sin θ = n sin θ mλ mλ= ntcosθ sin θ m = a dθ = dλ m acos θ m dl dλ = f dθ dλ hc λ = mv +ω A = 0.6λf ρ= r log ( T ) R R TE TM sin = sin tan = tan ( θi θt) ( θ + θ ) i t ( θi θt) ( θ + θ ) i t n tanθ B = n n sinθ c = n λ Δ θ = R = λ mn Nacosθ m Δλ

2 CHM 44 EXAM FALL 006 Name Score /50 30 pts.. Provide the following definitions or facts at 6 pts each. a. Label six of the regions of the electromagnetic spectrum b. List the types of transitions that occur in each of the regions you labeled in (a) (i) (ii) (iii) (iv) (v) (vi) Exam, 006, page

3 c. Light impinges on an interference filter perpendicular to its surface. As the angle of incidence increases, what happens to the wavelength of transmitted light? d. Consider the situation where a lens transfers the source image onto the entrance slit of a monochromator. What will happen if the lens has an f-number greater than the monochromator value? Less than the monochromator? e. Name one aberration that exists in a lens that does not exist with a mirror. Name one aberration shared by both lenses and mirrors. Exam, 006, page

4 30 pts.. Perform the following calculations at 0 pts each. a. A signal with an unknown frequency is digitized at 00 Hz, with the result aliased to 0 Hz. When the same signal is digitized at 0 Hz, the alias is 8 Hz. What is the actual frequency? b. If an object is cm from the lens and the image is 4 cm from the lens, what is the lens focal length. c. 600 nm light has a first order diffraction from a grating of 0E. How many lines per millimeter characterize the grating? Exam, 006, page 3

5 30 pts. 3. Answer the following two homework questions for 5 pts each. a. The silver iodide bond energy is approximately 55kJ/mol (AgI is one of the possible active components in photgray sunglasses). What is the longest wavelength of light that is capable of breaking the bond in silver iodide? b. Calculate the reflective loss when a beam of light passes through an empty quartz cell assuming the refractive index of quartz is.55. Exam, 006, page 4

6 30 pts. 4. The drawing at the right (not to scale) loosely depicts a microscope with an Amici objective and a CCD camera. This particular Amici objective is a -cm diameter hemisphere of glass with a refractive index of.5. For the following questions use thin-lens equations, even though they are not valid. (a) What is the focal length (Hint: you need to ask what radius would yield a flat lens surface?) and (b) f/# of the objective? (c) What is the focal spot radius at λ = 500 nm (0.5 μm)? Give the answer in micrometers. The CCD camera has pixels that are 9 9 μm. The biconvex lens has to be chosen so that a circular focal spot just fits onto a single pixel. (d) What is the required focal length of this lens? (e) Why can't a full sphere be used as the objective to get an even smaller spot size? CCD camera objective sample surface Exam, 006, page 5

7 30 pts. 5. Flash analog-to-digital converters are used to digitize very fast signals. They are expensive because each voltage level has a comparator. The signal reaches all comparators at the same time, thus the time required for conversion is much less than the successive approximation device in the class notes. The device shown in the figure is a 3-bit converter with eight levels of voltage resolution (0 through 7). Assume the comparators are wired so that V in $ V ref outputs +5 V (binary ) and V in < V ref outputs 0 V (binary 0). a) Use Ohm's law to determine the reference voltage for each comparator. Write the voltages next to each comparator. b) For each input voltage in the following table, determine the output (0 or ) of each comparator. Then use the table to state clearly how the value of the voltage is determined from the collection of comparator outputs. Part (c) is on the next page. V in Comparator Output (0 or ) C C C3 C4 C5 C6 C Exam, 006, page 6

8 c) The digital logic that converts the comparator outputs from the table into a three digit binary number (000 to ) is called an 8-line to 3-line priority encoder. One specific device that does this is a National Semiconductor 74F48 integrated circuit. Its digital logic can be solved but not on a test! If there are only three comparators being converted (as shown in the figure) the logic is much simpler because only a two-bit binary number results. V in 0 3 binary out Each bit in the binary output has its own logic that depends upon the comparator outputs (for a two-bit number, the right bit is called bit 0 and the left bit is called bit ). Use the inputs from comparators C through C3 to create two separate boolean logic expressions that yield the correct outputs. The only operators you will need are NOT, AND and OR. Make liberal use of parentheses to clarify the digital logic. 0.5 k.0 k.0 k 0.5 k +3.0 V V in +! +! +! C3 C C 0 Exam, 006, page 7

CHM 424 EXAM 2 - COVER PAGE FALL

CHM 424 EXAM 2 - COVER PAGE FALL CHM 44 EXAM - COVER PAGE FALL 007 There are six umbered pages with five questios. Aswer the questios o the exam. Exams doe i ik are eligible for regrade, those doe i pecil will ot be regraded. coulomb