Magnetism

1. Magnetism 012-11001 r1.04

2. Magnetism Introduction Each page of this lab that contains the symbol should be inserted into your journal. After completing a lab page with the snapshot symbol, tap (in the upper right corner) to insert the page into your journal. Journals and Snapshots The Snapshot button is used to capture the screen. The Journal is where snapshots are stored and viewed. The Share button is used to export or print your journal to turn in your work. Note: You may want to take a snapshot of the first page of this lab as a cover page for your journal.

3. Magnetism Lab Challenge Investigate the strength of a magnetic field from a permanent magnet as a function of distance.

4. Magnetism Background The strength of a magnetic field varies with distance from a magnet. The strength of a magnetic field could vary inversely as the square of the distance, similar to the strengths of gravitational and electric fields...

5. Magnetism ...Background ... or, the strength of a magnetic field could vary in a different way relative to distance. Unlike gravitational fields that are radial, a magnetic field consists of complete loops that surround and go through the magnet.

6. Magnetism Materials and Equipment Collect all of these materials before beginning the lab. • Magnetic field sensor • PASPORT extension cable • Neodymium Magnet (1/2 or 3/4") • Meter stick

7. Magnetism Sequencing Challenge The steps to the left are part of the procedure for this lab activity. They are not in the right order. Determine the correct sequence of the steps, then take a snapshot of this page. A.Place a magnet next to the 5 cm mark on the meter stick with the north pole of the magnet facing the sensor. B.Place the magnetic field sensor so the end of the rod is even with the zero end of the meter stick. C.Proceed to data recording and manual sampling for every 1 cm increase in the magnet's position up to 15 cm. D.Place a meter stick on a flat surface.

8. Magnetism Setup • Set the meter stick flat on a lab table. • Connect the magnetic field sensor to the SPARK Science Learning System using the PASPORT extension cable. • Set the magnetic field sensor on the lab table so that the tip of the sensor meets the 0 cm marker on the meter stick.

9. Magnetism Setup • Hold the magnet far away from the magnetic field sensor, then press the Tare button on the sensor. • Note:If your sensor does not have a Tare button, proceed to the next step. • Set the magnet on the lab bench against the meter stick, with either flat face pointed towards the tip of the magnetic field sensor. • Slide the magnet up the meter stick until it is aligned with the 5 cm marker on the meter stick (5 cm away from the tip of the sensor).

10. Magnetism Collect Data Q1: Why do you think it is important to have the tip of the magnetic field sensor pointed at the middle of the magnet, rather than off axis?

11. Magnetism Collect Data • On the next page is a table with one column already populated with data. This data represents the different distances between the magnet and sensor at which you will measure the field strength. • Be sure that the actual distance between the magnet and sensor matches what is specified in the table before recording each data point. This number should match the actual distance between your magnet and the sensor. Note:If your magnetic field measurements are negative, turn the magnet around such that the North end is pointing towards the sensor.

12. Magnetism Collect Data • Tap to begin data collection. • Set the distance between the sensor and the magnet to match what is specified in the table. • Tap to record the magnetic field strength at that distance. • Move the magnet to the next distance specified in the table and repeat the previous step until you have reached 15 cm.

13. Magnetism Collect Data • Tap to stop data collection Q2: The magnetic field sensor measures the axialfield strength component from the magnet. What do you think the magnitude of the radial (perpendicular) field strength component would be without actually measuring it? Radial Axial Radial (perpendicular)

14. Magnetism Prediction • Draw a prediction of how you think your magnetic field strength versus distance data would look in a graph. *To Draw a Prediction: 1. Tap to open the tool palette. 2. Tap then use your finger to draw your prediction. 3. Tap when finished. 4. If you make a mistake, tap to clear your prediction.

15. Magnetism Analysis • How does the actual graph compare to your prediction on the previous page? Is this what you predicted?

16. Magnetism Analysis • From the graph, what do you conclude is the mathematical relationship between the magnetic field strength and distance?

17. Magnetism Analysis • Apply a "Power" curve fit to your data. • Note: The form of the curve fit will be y=Axn+B (n can be negative) *To Apply a Curve Fit: 1. Tapto open the tool palette. 2. Tapto open the Curve Fit screen. 3. Tap the name of the curve fit required.

18. Magnetism Analysis • How well did your curve fit match your data? Was the mathematical relationship you chose representative of the theoretical relationship? If not, what do you think the real relationship is?

19. Magnetism Synthesis • The needle in a compass acts like a tiny bar magnet. When the needle is in the presence of a strong magnetic field, it will align itself with that field. If the red end of the needle represents the south pole of the "magnet," which direction would the red end point if the compass were placed between the poles of this magnet? To the left, or to the right?

20. Magnetism Synthesis • If you had two identical magnets separated by distance d with the north pole of each magnet facing the other, what value would your magnetic field sensor read at distance d/2? d

21. Magnetism Synthesis • If each magnet alone produces an axial magnetic field strength of 0.25 T at a distance d/2, what value would your magnetic field sensor read at a distance d/2 if the north and south poles were facing each other a distance d apart? d

22. Magnetism Synthesis • How will the magnetic field strength measured half way between the magnets change (increase, decrease, or stay the same) if the distance between the magnets is increased from d to 10d? 10d

23. Magnetism Multiple Choice Question • A compass is positioned at a location near the north pole of a bar magnet and moved around the magnet toward the south pole. How does the compass needle orient itself at the south pole? • The compass orientation does not change • Not enough information • Points towards the south pole • Points outward from the south pole

24. Magnetism Multiple Choice Question • As the magnitude of the magnetic field from a permanent (disc) magnet increases, the position of the sensor from the magnet will: • increase • decrease • remain the same • decrease to zero

25. Magnetism Congratulations! You have completed the lab. Please remember to follow your teacher's instructions for cleaning-up and submitting your lab.

26. Magnetism References ALL IMAGES WERE TAKEN FROM PASCO DOCUMENTATION, PUBLIC DOMAIN CLIP ART, OR WIKIMEDIA FOUNDATION COMMONS: http://commons.wikimedia.org/wiki/Image:GPB_circling_earth.jpg http://commons.wikimedia.org/wiki/Image:N.Tesla.JPG http://commons.wikimedia.org/wiki/Image:DIN_4844-2_Warnung_vor_magnetischem_Feld_D-W013.svg http://commons.wikimedia.org/wiki/File:Feeling_magnetic_repulsion.JPG http://www.freeclipartnow.com/office/paper-shredder.jpg.html http://www.pdclipart.org/compass1/chainnicubuculei01 http://freeclipartnow.com/construction/tools/magnet-with-nails.jpg.html http://freeclipartnow.com/construction/tools/screws.jpg.html http://freeclipartnow.com/construction/tools/locks/keyring.jpg.html