Magnetic Fields

Activity HO-14A

Assigned: Day 14, Oct. 14, 1997

Open a Word file to record the answers to the questions in the following activities.
Enter the names of all the members of your group in your Word file. Label it HO-14A,
Magnetic Fields

HO Activity 1: Bar Magnets

Place one bar magnet on the table, and cover it with a piece of paper. Trace the
outline of the magnet on the paper so you know how it is oriented. Sprinkle a modest
amount of iron filings on the paper, enough so you can see a pattern form. It may help to
lightly tap the paper. Sketch and label the shape of the pattern formed by the iron filings
in your notes. When finished, you can use the paper as a funnel to pour the iron filings
into their container.

1. Briefly describe the pattern made by the iron filings.

Compasses are, in a way, just a fancy piece of iron filing.
they will point along a magnetic field line.

They are made such that

Place your compass on the table, away from any wires, power supplies, or magnets.
Note which direction the compass points. Some of the compasses have been altered and
point in the "opposite" direction. This is not a problem as long as you know which way
is North, and note which end of the compass needle points that way. With thestrong
magnets we will be using, the compasses might "flip" during lab, so you should recheck
them occasionally.

2. Go in the hallway with a compass. Which way does it point? Why?

3. There is one magnetic field we cannot do too much about - the Earth's. In this lab,
   the field we create will usually be stronger than the Earth's field. Will a compass
   indicate the stronger field, or some combination of both? Why do you think so?

Use the compass to find the direction of the magnetic field at various locations
around the bar magnet. Add direction arrows to your sketch of the magnetic field.

4. Based on your sketch, where does it appear the magnetic field is strongest?
   it weaker? How can you tell?

Where is

By convention, we say that the field lines come out ofthe "North" magnetic pole
of the bar magnet and enter the "South" magnetic pole. On your sketch, label one end of
the bar magnet with N and the other with S to indicate which end is the North pole and
which is the South pole.