Lab 8: Magnets and Electromagnets 1. This simulation allows you to experiment with magnets and learn about how magnetic fields vary in strength. To access the simulation, use the PHJ simulation found at: https://phet.colorado.edu/en/simulation/legacy/magnets-and-electromagnets You will need to run the simulation on your computer; most systems will simply open the simulation, but you may need to download it and run it to get the simulation to work. The PhoJ. website is well known and safe. Downloading and using the simulations on this site will not harm your computer. 2. First, observe the magnet. The tiny compasses (the little diamonds in the background) show the direction of the magnetic field lines around the magnet. The red side of the compasses points north, and the white end points south. Draw the magnet below and sketch the magnetic field lines. Mark N/S on the field lines (magnetic field lines are always drawn with arrows pointing from north to south). What do the magnetic field lines inside the magnet look like? If you include these lines, describe the overall shape of the field (inside and outside of the magnet). Are the field lines open lines or closed loops? Move the magnet around. What happens to the background as you move the magnet? What happens to the shape of the magnetic field? Select "Show field monitor". Measure the magnetic field close to the south pole of the magnet and close to the north pole of the magnet and record your values for B here: South North: 6. Now move the magnet to the top of the screen and place the field monitor just below it, in the center of the magnet. Starting just below the center of the magnet, there should be 13 curved rows of tiny background compasses. Place the field monitor on each of these circles, and record the value of the field in the table below. Row Value of Field (G) Asuming that the distance between the rows is 1.25 cm, calculate how much the field should decrease between the first and second rows, assuming that the starting value is 3.66 G. Remember that the magnetic field follows an inverse square rule, so you should divide 3.66 by 1.25^2: Record your answer here: This number should be similar.to the 2nd value of the magnetic field you recorded in the table in question 6. 8. Now calculate how much the field should decrease from the first row to the last row. First, calculate the distance from the first row to the last row by multiplying the distance between rows by 12 (the number of rows - 1). Record the distance here: Next, calculate how much the field should decrease from the starting value of 3.66 using the inverse square law by dividing 3.66 by the total distance squared. Record your answer here: This number should be similar to the last value of the magnetic field you recorded in the table in question 6. 9. Compare your answers in 7 and 8 to the values of the field you measured in the 2"d and 13th rows of the table in question 6. Calculate the percent error for each of these values, assuming that the measured values are the real values, Show all work here. 10. How close were your calculated values? What may have caused the errors? 11 Summarize what you have learned about magnetic fields in this lab. (3-5 sentences)
