Electromagnets

Shirley Porter-Cesair          Charles R. Henderson
                               5650 So. Wolcott
                               Chicago Il 60636
                               (312) 535-9080

Objective:
 
The students will make an electromagnet and determine the strength of the 
electromagnet.

Materials Needed:

Small Compasses
Three feet of insulated copper wire per person
Six-volt battery
Size D batteries
Battery Holders
Pieces of Cardboard
Nails (3 inches or longer)
Paper clips, tacks, pins, or other small magnetic objects
Iron filings
Salad oil
Glass or plastic cylinder (100 ml)
Wrought iron stand

Strategy:

 Activity 1

Students will work in pairs.  Each pair of students will receive a baggie 
containing materials needed.  Allow the students ten or fifteen minutes to 
explore and manipulate the materials.  Have one student from each group connect 
their compass with wire through the holes in the cardboard.  Insert the wire 
through the Fahnestock clips on both ends.  Place the wire over the compass.  
What happens and why?

Concept:

The electrical current flowing through a wire will create a magnetic field.  
This magnetic field causes the needle to turn at a right angle to the wire.  
Reverse the connections to the battery, thus reversing the direction of the 
current flow, and the needle will point in the opposite direction.

Activity 2

Using the same bag of materials, the pairs of students will begin wrapping the 
wire around the nail in the same direction until a foot of wire is left at both 
ends.  Insert the end wires into the Fahnstock clips.  Hold the electromagnet 
over a small pile of paper clips, tacks or other small metal objects.  How many 
objects does your electromagnet attract?  Take the wire off the battery 
terminal, and the tacks will immediately fall off.


Concept:

The current passing through the wire produces an invisible magnetic field.  When 
the current is cut off, the magnetic field disappears, then the molecules of 
the iron return to their helter-skelter position and the nail loses most, but 
not all, of its magnetism.

Performance Assessment:

As a result of the electromagnet mini-teach, the sixth grade students will be 
able to describe the characteristics of a magnet and an electromagnet.  Both 
attract metal and have magnetic fields; the electromagnet needs an electrical 
current.     

The students will be able to make an electromagnet with a wire, a battery, and 
a nail.

The students will be able to test the strength of the electromagnet by using 
more coiled wire and additional batteries and nails.

Conclusions:

In activity 1 we found that electricity can produce magnetism and magnetism can 
produce electricity.  The opposite ends or poles of magnets are attracted to 
each other and like ends repel.

In activity 2 we found that current through a wire produces an invisible 
magnetic field.  When the current is cut off, the magnetic field disappears, 
then the molecules of the iron return to their helter-skelter position and the 
piece loses most, but not all, of its magnetism.

References:

Safe and Simple Electrical Experiments. Rudolf F. Graf.  Dover Publications, 
Inc.,N.Y., 1964.  pps. 86-88 and 93-94.

Be a Kid Physicist.  William R. Wellnitz, Ph.D.,  Tab Books.  McGraw-Hill, Inc., 
Blue Ridge Summit, PA. 1993.  p, 82. 

Science Projects About Electricity and Magnets.  Robert Gardner.  Enslow 
Publishers, Inc., N.J., 1994.  pps. 72-82.