\fof 5 Faraday's Law EVALUATION OF DATA 1. Using the expressions for Faraday's law and for the strength of the magnetic field near the center of a solenoid, derive an equation that relates the value of the emf in the secondary to the rate of change of the current in the primary. 2. Obtain information about the number of turns in your primary solenoid. Measure the length of the primary and the diameter of the secondary. Use these values to determine a value for all the terms except for the rate of change of current in the primary. 3. Examine the graphs for the run in which you used a triangle waveform to drive the current in the primary solenoid. Find the slope of the current vs. time graph for an interval in which the current was increasing or decreasing steadily. 4. Use the values from Steps 2 and 3 to determine the expected value of the induced emf for the corresponding interval of the potential vs. time graph. 5. Select this interval on the potential vs. time graph and choose Statistics from the Analyze menu to determine the mean value of the emf during this interval. How does the experimental value compare to the value you calculated in Step 4? Can you account for any meaningful difference? EXTENSIONS 1. Create a calculated column in which you find the derivative of the current with respect to time. Add this column to your graph of the induced voltage vs. time. Describe your findings. 2. What effect would winding more turns on the secondary coil have on the graph of potential vs. time? Test your prediction. 3. What effect would moving the secondary coil to the end of the solenoid have on the magnitude of the induced emf? Test your prediction, then explain your findings. 4. Repeat the experiment using a square waveform to drive the current in the primary solenoid. Ei 78OF Mostly sun4. Use the values from Steps 2 and 3 to determine the expected value of the induced emf for the corresponding interval of the potential vs. time graph. 5. Select this interval on the potential vs. time graph and choose Statistics from the Analyze menu to determine the mean value of the emf during this interval. How does the experimental value compare to the value you calculated in Step 4? Can you account for any meaningful difference? EXTENSIONS 1. Create a calculated column in which you find the derivative of the current with respect to time. Add this column to your graph of the induced voltage vs. time. Describe your findings. 2. What effect would winding more turns on the secondary coil have on the graph of potential vs. time? Test your prediction. 3. What effect would moving the secondary coil to the end of the solenoid have on the magnitude of the induced emf? Test your prediction, then explain your findings. 4. Repeat the experiment using a square waveform to drive the current in the primary solenoid. Explain the shape of the graph of potential vs. time in the context of an LR circuit. 78-F Mostly sunny