In lab 2 you became familiar with how charged particles move in the presence of a constant, uniform electric field, with or without a "friction" or resistance force. Electrons moving through a circuit is one example of charges in an electric field with a resistance force present; today you will study a second. Electrophoresis refers to the motion of charged particles in an electric field, moving within a fluid that provides a frictional force, opposing their motion. It is often applied in biology labs to separate DNA or protein molecules by charge and weight. Refer to the image below, and note the similarity to the setup you used in lab 2A! You are working in a biology lab that uses electrophoresis, and have started to suspect that there is something wrong with your experimental apparatus, since you are unable to produce the expected results on test runs. You begin trying to diagnose the problem, first by removing the gel (fluid) and obserVing the motion of charges within the apparatus. If the apparatus is working correctly, there should be a constant and uniform electric field between the electrodes. which of the foilowmg observations would tell you that the apparatus is, in fact, producing such a field? Remember, the gel (friction) has been removed. O A charged particle placed in the apparatus moves with constant acceleration. O A charged particle placed in the apparatus does not move at all. (9 A charged particle placed in the apparatus moves with constant velocity. 0 A charged particle placed in the apparatus begins to oscillate back and forth as ifit were on a spring. X You can readily observe the velomty of a charged particle placed in the apparatus (usmg variety of techniques such as electophoretic light scattering or TRPS). There is still no gel (friction) in the apparatus when you collect the following data with a particle of mass 1 kg and charge *1 C: Position (cm) Velocity (m/s) 0 0.44 0.65 0.85 1.01 1.25 1.49 1.79 2.22 2.86 10 4.28 \\DmHIO'lUI-JALJNHO Your goal is to use the velocity vs. position data to reconstruct a map of voltage vs. position and ultimately electric field vs. position. Recall that we can use conservation of energy to relate velocity and voltage in a case like this one where electric potential energy is converted to kinetic energy. With this in mind, what is the voltage difference between the two electrodes in your apparatus? Assume that the particle (in : 1 kg, g : 1 C) starts at the grounded electrode (V : 0 V). :lv You can apply the same logic to determine the voltage difference between any two points for which the velocity is known. Again, assume that the particle (in : 1 kg, 1: : 1 C) starts at the grounded electrode (V : 0 V). By considering successive points, use your velocity data to produce a map of voltage vs. position between the electrodes. Make sure the axes on your graph are labeled and display the correct numerical values. Upload your graph below (PDF, JPG, PNG, or GIF). HINT: It may save you some time if you set up a calculation in Excel or Capstone rather than repeating the work by hand for each pair ofpoints. Choose File No file chosen Finally, using your voltage map, produce a plot of electric field as a function of position in your apparatus. Make sure the axes on your graph are labeled and display the correct numerical values. Upload your graph below (PDF, JPG, PNG, or GIF). HINT: What is the mathematical relationship between electric field and voltage? Choose File |No file chosen This answer has not been graded yet. In the field below briefly describe the physical principles and equations you used to produce each graph and the procedure in Excel/ Capstone/ etc. to arrive at your finished graphs. This answer has not been graded yet. As a conclusion, based on your graphs, is the electric field between the electrodes uniform as expected? Explain how you can tell. Give an example of a charge / charge distribution that produces a uniform electric field, and one that produces a non-uniform electric field