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# Sample_Exam_Questions_Answers - P = hf ISample Exam...

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P = hf - ½ mv 2 P = I 2 R Sample Exam Questions Solutions Problem #1 (4 points each) Given the MATLAB commands below: >> a = [ 1 , 2 ; 8 , 9 ] >> b = [ a(:,2) a(:,1) ] a) What values populate a after the first line of code? = a 1289 b) What values populate b after the second line of code? = b 2198 Problem #2 (4 points each) Given the MATLAB commands: >> S = [0:5:35] >> S = S.^2 a) What is the value of S(3)? 100 b) How many numbers does the vector S contain? 8 Problem #3 (4 points) Which of the following MATLAB commands will result in MATLAB producing an error? (Circle all that apply.) a)5 = a b)plot( x , y , ‘line’ ) c)G = 5.*G + 1 d)b = log(0) e)1st-data-run = [18.2 18.5 18.3 18.2] f)H(1,2) = 5 Problem #4   (4 points each) In the photoelectric effect, light may cause electrons to be ejected from a metal surface. The equation below calculates P , the work to remove the electron from a material (its work function): Where m is the electron mass, v is the velocity of the ejected electron, f (the frequency of the incident light, and h is the Planck’s constant.

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a) What formula can be typed into cell F3 and copied to cells F4:F8 to calculate the work function of each material from electron velocities in E3:E8 and constants in column A? =\$A\$2*\$A\$8 – (1/2)*\$A\$5*E3^2 b) Write a formula that can be typed into cell E9 to calculate the average/mean electron velocity of these surface materials so that the formula could be copied to F9 to compute the average/mean work function for these materials. =AVERAGE(E3:E8) c) Complete this script with MATLAB code to calculate the work function of each material. % Input Section h = 6.63e-34 % Planck’s constant m = 9.11e-31 % electron mass f = 1e17 % light frequency v= [ 1.1993e7 1.1987e7 1.2001e7 1.1988e7 1.1968e7 1.1992e7] % electron velocities % Calculation Section work = h*f – (1/2)*m*v.^2 d) How would we change the code in c) to prevent the assignment of h, m, f, and v from displaying in the command window? Put a SEMICOLON at the end of each line e) Write the MATLAB commands to produce a plot of the relationship between work function and electron velocity. Make sure your plot is suitable for presentation.
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