Download Electromagnet Mania

Electromagnet Mania
Indiana Expeditions Show
Physical Science
Overview
Students will build and test their own electromagnet and then experiment with variables
to see if they can change the strength of their electromagnet.
Background information:
Electromagnets are practical tools that are used in many everyday applications. For
example, electromagnets can be found in the motors of CD players that keeps the CD,
power windows in cars, and automatic doors. In recycling facilities they are used to
separate ferrous materials (those containing iron) from non-ferrous materials.
The most basic electromagnet (see figure 1) consists of a coil of wire through which an
electric current is passed. Electromagnets are useful because their magnetic field
depends entirely on the flow of electric current through the electromagnet. If electricity
is flowing through the electromagnet, a magnetic field will be produced and the
electromagnet will attract ferrous materials. If the flow of electricity stops, the
electromagnet ceases to produce a magnetic field and any attracted materials will be
released. Thus, the magnetic force can be controlled or turned on and off.
The strength of an electromagnet’s magnetic field can be changed by changing the parts
that comprise the electromagnetic (for example: the number of coils in the wire of the
electromagnet, the voltage flowing through the electromagnet, etc.). Thus, it is possible
to make electromagnets with different magnetic fields for different practical applications.
Fig. 1: A Basic Electromagnet
Connections to the Indiana Academic Standards for Science
3.1.2, 3.1.4, 3.1.5, 3.1.6, 3.1.7, 3.2.5, 3.2.6, 3.2.7, 3.6.1, 3.6.2, 4.1.3, 4.1.8, 4.1.9,
4.2.3, 4.3.15, 4.6.1, 4.6.2, 5.1.5, 6.1.3, 6.1.4, 6.1.5, 6.2.4, 6.2.23, 7.1.7
Science Process Skills
 Communicating
 Developing hypotheses
 Identifying and manipulating variables
 Interpreting data
 Measuring
 Observing
 Posing questions
 Predicting
Estimated Time Requirement
One 45- minute session
Materials
 One magnet
 One “Recycling Center” as described in the “Preparation prior to the lesson”
section below
 Wire cutters
 Enough 24” pieces of insulated copper wire for one piece per group of three
students
 One D-cell battery per group of three students
 One 3” or longer nail per group of three students
 Extra D-cell batteries
 Several nails and bolts of different lengths and diameters
 Extra wire
 Several paperclips per group of three students
 Masking tape (optional)
Objectives
Students will be able to
1. describe an electromagnet.
2. modify an electromagnet to increase the strength of its magnetic field.
Procedure
Preparation prior to the lesson:
 Cut a 24” length of insulated copper wire for each group of three students. Strip
about ½” of insulation off each end of the wires.
 Prepare a “recycling center” by placing several small items that are attracted to a
magnet and several small items that are not attracted to a magnet inside a clear
container and mixing them together. For example, place several paperclips,
staples, scraps of paper, rubber bands, aluminum pop can tabs, erasers, and other
small items in a clear baking dish.
Anticipatory set:
 View the Physical Science Indiana Expeditions segment.
 Ask students to predict what will happen if you swirl a magnet through or above
the “recycling center”. Try it. Now ask the students how to get the materials off
the magnet. Explain that in a real recycling center there must be a cost- and
time-efficient way to separate the ferrous metals from the non-ferrous materials.
Tell students that they are going to build a device that will do just that!
Lesson sequence:
 Divide the students into groups of three. Give each group: one 24” length of
insulated copper wire, one D-cell battery, one three-inch or longer nail, several
paperclips, masking tape (optional)
 Instruct students to construct an electromagnet, following the directions below:
o Wrap the wire tightly around the nail about a dozen times.
o Hold one end of the coiled wire against the positive end of one D-cell
battery. Hold the other end of the coiled wire against the negative end of
the same D-cell battery. (Note: If desired, wires may be taped with
masking tape to the battery.)
o Students have now created an electromagnet.
 Tell students to test their electromagnet by attempting to pick up a paperclip
with the pointed end of the nail.
 Discuss how the electromagnet works with students.
 Direct students to pick up a paperclip with their electromagnet and then, while
holding the paperclip in the air with their electromagnet, remove one end of the
wire from the battery. Discuss the results.
 Challenge the students to see how many paperclips they can pick up with their
electromagnet and to explore ways to increase the strength of their
electromagnet’s magnetic field. Point out the extra D-cell batteries, different
nails and bolts, and additional wire students may used to meet this challenge. If
desired, ask the students to draw up a plan and get it approved prior to testing
their idea. CAUTION: Increased current flowing through the electromagnet can
cause an increase in the heat that is lost from the system. Parts of the
electromagnet MAY BECOME HOT!
 Allow students to explain to their classmates how they increased the magnetic
field of their electromagnet.
 As a class, discuss the factors that influence an electromagnet’s magnetic field
and why it might be useful to be able to control the force of an electromagnet.
Closure
 Revisit the “Recycling Center” and use an electromagnet to pick up and then
release several of the items from the center. Discuss the practical applications of
the use of electromagnets.
Suggested Student Assessment
Objective #1:
Students verbally describe or write an explanation, including illustrations, of the
structure and function of a simple electromagnet.
Objective #2:
Provide students with an already-constructed electromagnet and have them
demonstrate how many paperclips the electromagnet will pick up. Instruct them
to modify the electromagnet using only the supplies they have (from the already
constructed electromagnet) so that the electromagnet will pick up an additional
paperclip.
Extending the Lesson:
 Explore how the use of different gauges of wire or different voltage batteries
effect the strength of the electromagnet. Be sure to emphasize the importance of
changing only one variable at a time and the importance of repeated trials.
 Ask students to investigate and report on some common applications that use
electromagnets. Students can bring in items that contain electromagnets and
explain the role of the electromagnet in the functioning of the item.
Source of Lesson
Deb Sachs
Director, Office of Professional Development
School of Education
University of Indianapolis