Mapping a Magnetic B Field
Obj:   Establish magnetic B field lines around magnets
Materials:   bar and horseshoe U magnets, compass
Methods

I.   Bar Magnet
1.  Determine the true north and south poles of your magnets using a magnetic compass.  Place a bar magnet centered on your blank paper and outline its shape.  Label the N/S poles.
2.  Draw one closed loop field line at a time by placing the button compass near one corner of the N pole.
3.  Mark on your paper where N & S of the compass are aligned S w/ N; mark again.
4.  Repeat for a total of 8 lines, 4 on each side of magnet's axis.  Complete the closed loop field lines by running the field line through the magnet from south to north.  Show arrows correctly inside and outside the magnet.

II.  2 Bar Magnets
1.  Align N & S poles of  magnets about 15 cm apart.  Repeat the mapping method described above between the two poles.   Show arrows correctly.
2.  Align N/N or S/S.  Repeat the mapping method.  Show arrows correctly.

III.  Horseshoe Magnet (Demo)
1.  Sketch the iron filing demonstration.  Label the N & S poles with appropriate arrows.

Analysis
1.  Where are the magnetic field lines closest?  What does this imply?
2.  Discuss the lab evidence obtained on your data sheets for attraction and repulsion of magnetic poles. (Hint: look at the field lines and your arrows).
3.  In your summary, discuss the magnetic field and its similarities and differences with electrical fields and gravitational fields.  Do field lines ever cross?

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