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.

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 “RecyclingCenter” 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 eachgroup: 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:
  • Wrap the wire tightly around the nail about a dozen times.
  • 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.)
  • 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 workswith 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 “RecyclingCenter” 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 ProfessionalDevelopment
School of Education
University of Indianapolis