Info Bulletin Physics 30 2009-2010 - McCoy High School

Method 2Calculator active solution:Determining the focal length using graphical analysisCalculator active solutionstore1in L1, in units of m –1d ostore1in L2 in units of m–1d iperform the linear regressiony = ax + b on L1, L2to give a = –0.967b = 3.91Window settings on calculatorx:[0, 2.5]y:[0, 5]The variable plotted on the y-axis is the reciprocal of the image distance,The variable plotted on the x-axis is the reciprocal of the object distance,1di1doThe physics equation is1f=1do+1di1 1=f d1dio1+d1= –doi+1fy = m x + b1Therefore, the y − intercept = , which givesff = 1 10.26 m– 1y-intercept=3.9 m= (mark consistent with the student’s graph)or using the calculator active solutionf = 1 10.26 m– 1y-intercept=3.91m= (2 S.D.’s as per data chart)33