PHYS 102 - Lab 4 - Motion of charged particles in E and B Fields - WORKSHEET (Known values: e = 1.602 E-19 C, me = 9.11 E-31 kg) Parameters for apparatus N = 130 Calculate the speed of electrons accelerating across a 250 V potential difference (show work). Calculate the required current in the Helmholtz coils to achieve ~10-3 T magnetic field (show work). Suppose the magnetic field is 103 T, and the accelerating voltage is 250V. Using known values for e and m, calculate the expected radius of the electrons' orbit (show work). Data Analysis: Use an Excel workbook to record measurements of the electron orbit radius for varying accelerating voltages and Helmholtz coil currents, and use these values to make a prediction for
the e/m ratio of an electron. Turn in your Excel file with this worksheet. Write your prediction below. (Hint: in the spirit of the previous two labs, find a way to plot the data such that your e/m prediction is given by the slope of a line) Compare your prediction to the expected value and report its accuracy as a percent error. Is your result accurate? Explain your reasoning. Identify and explain at least two possible sources of uncertainty in this experiment. (Note: Be clear and specific in your answer. A vague response such as "human error" will receive no credit unless you clarify exactly what that means.)