Name:__________________________________________Date:____________________
Magnetic Fields: Laboratory Activity
Materials (per group) 2 permanent bar magnets, small compass, pencil, horseshoe magnet,
sheet of paper, iron fillings
Purpose: To investigate and analyze magnetism and the practical application of the
characteristics of magnets
Procedure (Part 1):
1. Center one bar magnet in the middle of the large sheet of paper. Trace around the
magnet. Place the compass near the ends of the bar magnet. Place an arrow to show
the direction of the needle on the compass. Move the compass to observe how the
compass needle changes direction.
2. Sprinkle iron fillings on the paper until you can see the magnetic field lines. Sketch
your observations below on the Magnetic Field Section.
Procedure (Part 2):
1. Place two textbooks side by side, about 7 cm apart.
2. Place the magnets between the books, with north poles facing, about 2 cm apart.
Place the compass near the ends of the bar magnet. Place an arrow to show the
direction of the needle on the compass.
3. Place the paper over the magnets to form a bridge.
4. Sprinkle iron fillings on the paper until you can see the magnetic field lines. Sketch
your observations below.
5. Carefully return the fillings to their container.
6. Repeat Steps 2 through 7 with opposite poles facing.
7. Place a paper over the horseshoe magnet and observe the direction of the compass
needle. Make direction arrows on the diagram below. Sprinkle iron fillings (focus
towards the ends of the horseshoe magnet). Draw your field lines on the diagram
below.
Magnetic Field Draw a pattern of magnetic fields around these magnets.
Part 1:
Part 2:
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Horseshoe magnet:
Turn to a neighbor and explain to them what happens when a north and
North Pole touch. Then explain what happens when a north and South Pole touch.
Independent Practice-Magnets:
1. What does a magnet repel?
a)
The opposite pole of another magnet
b)
Iron, nickel and cobalt
c)
The same pole of another magnet
2. What happens if you cut a magnet in half?
a)
It destroys its magnetism
b)
You get a North Pole magnet and a South Pole magnet
c)
You get two magnets, each with a N and S pole
3. Why does a compass point north?
a)
The shape of the Earth causes it
b)
There is a large deposit of iron right at the North Pole
c)
The Earth is a large magnet with a magnetic pole near the North Pole
4. Draw a diagram to illustrate what happens when you move two unlike magnetic poles
closer together.
5. Where is the magnetic field the strongest? How do you know?
The Characteristics of an Electromagnet
When a conducting (insulated) wire is coiled around a piece of soft iron, and electric current is passed
through the coil, the soft metal then becomes magnetic. This installation is called an electromagnet.
Unlike a permanent magnet, the magnetic strength of an electromagnet is temporary and will vanish
when the electric current is cut off. If the piece of soft iron is replaced by an iron nail, the magnetic
strength may last for several seconds to several minutes after the electric current stops, depending on
the composition of the iron nail.
1. How to make a simple electromagnet?
a. Coil a piece of insulated wire around an iron nail 40 times. Scratch off the protective coating on
both ends of the wire with sandpaper.
b. Connect the ends of the wire to the positive and negative poles of a battery to create the
electromagnet.
Iron nail
Scratch off protective coating
Battery
Insulated wire
1. What factors may affect the magnetic strength of an electromagnet?
2. How can an electromagnet’s strength be increased?
a. decrease the number of coils
b. decrease the voltage
c. use a plastic core
d. increase the number of coils