Data Acquisition: (Online lab: remember to use nominal values given above, p. 3-4) 4.) Open the Excel template provided for you for this lab. Locate the cell to enter the current flowing to your Helmholtz coil, and then use Excel to calculate (using eqn 4) the B field it causes in the region of the electron beam. If needed, consult the Excel reference materials from Lab #4 (especially the "How to Use Excel" document p. 1, section 2). Remember to include units in the adjacent cells, as requested in the template. (Online lab: the full data set for steps #5-6 is already provided for you.) 5.) Now, use the ruler mounted behind the apparatus to measure the radius of the electron beam (r) and record it and its corresponding accelerating voltage (should be 150 V to start) in the provided table. Program another column to convert "r" to SI units. 6.) Now increase this voltage to 200 V. Record the data for the new electron beam radius and accelerating voltage. Then repeat the process again at 250 V and 300 V, giving you a total of four pairs of values. Q2.) As you increase the accelerating voltage in the electron gun, does the radius of the beam increase, decrease, or stay the same? Explain why this is conceptually. Data Analysis 7.) In your Excel spreadsheet, insert an additional column to the left of your V column (important to facilitate graphing). In this column, calculate in Excel the radius of the beam squared (r ) for each trial. Remember to label the column header appropriately, including units. 8.) Make a graph of V vs. r (this means V on the vertical axis and r' on the horizontal axis). It should look reasonably linear. For how to graph (and what guidelines to follow), continue to consult Lab #4 and associated reference materials given there. Q3.) Examining eqn (3), why do we expect this graph to be linear? In theory, what should its slope be? Explain