Learning Activity

Changing the Strength of an Electromagnet

Subject Area

Science

Grade(s)

8

Overview

In this activity, students will design an experiment to test factors that affect the strength of an electromagnet.  

This resource was created as a result of the ALEX Resource Development Summit.

Science (2015) Grade(s): 8

SC15.8.11

Plan and carry out investigations to evaluate how various factors (e.g., electric force produced between two charged objects at various positions; magnetic force produced by an electromagnet with varying number of wire turns, varying number or size of dry cells, and varying size of iron core) affect the strength of electric and magnetic forces.

Unpacked Content

UP:SC15.8.11

Vocabulary

  • Investigation
  • Evaluate
  • Factors (e.g., electric force produced between two charged objects at various positions; magnetic force produced by an electromagnet with varying number of wire turns, varying number or size of dry cells, and varying size of iron core)
  • Force
  • Magnetic force
  • Electric force
  • Electromagnetic Force
  • Attraction
  • Repulsion
  • Magnitude
  • Charges
  • Currents
  • Magnetic strength

Knowledge

Students know:
  • The strength of electric forces can vary.
  • Cause-and-effect relationships affect the strength of electric forces. These relationships include the magnitude and signs of the electric charges on the interacting objects and distances between the interacting objects.
  • The strength of magnetic forces can vary.
  • Cause-and-effect relationships affect the strength of magnetic forces. These relationships include the magnitude of any electric current present in the interaction, or other factors related to the effect of the electric current (e.g., number of turns of wire in a coil), the distance between the interacting objects, the relative orientation of the interacting objects, and the magnitude of the magnetic strength of the interacting objects.
  • Electric and magnetic forces can be attractive or gravitational.

Skills

Students are able to:
  • Identify the phenomena under investigation, which includes objects (which can include particles) interacting through electric and magnetic forces.
  • Identify the purpose of the investigation, which includes which includes objects (which can include particles) interacting through electric and magnetic forces.
  • Develop a plan for the investigation individually or collaboratively.
  • Describe factors used in the investigation including appropriate units (if necessary), independent and dependent variables, controls and number of trials for each experimental condition.
  • Perform the investigation as prescribed by the plan.
  • Use data from the investigation to provide an causal account of the relationship between various factors and the strength of electric and magnetic forces.

Understanding

Students understand that:
  • Various factors affect the strength of electric forces.
  • Various factors affect the strength of magnetic forces.

Scientific and Engineering Practices

Planning and Carrying out Investigations

Crosscutting Concepts

Cause and Effect

Phase

During/Explore/Explain
Learning Objectives

Learning Objectives

After designing and conducting an investigation in which the basic components of an electromagnet are modified, students will be able to identify which factors affect the strength of the electromagnetic force.

Activity Details

  1. The teacher leads a class discussion where students brainstorm ways to strengthen the electromagnet. Ideas should be divided into three categories: battery, wire, and nail core.  Possible factors for investigation include but are not limited to the length of wire, the diameter of the wire, size/voltage of the battery, the brand of battery, number of batteries, number of loops of wire, size of the nail, or type of nail/core.
  2. Each group of students is assigned one of the identified ideas to test. Groups then collaborate to design and carry out an experiment to determine if their modification affects the electromagnet’s strength as measured by the number of paper clips picked up. Using the handout provided as a guideline, students should write a procedure and create a data table.

  3. Student groups report back to the whole class on the results of their experiment.  Students use this information to create a T-chart to identify factors that do and do not affect the strength of an electromagnet.

     

     

     

     

  4. Students view the video clip How an Electromagnet Works and compare the class results to the video.

 

Assessment Strategies

Assessment Strategies

Students use a template to report their findings of the electromagnet experiment.

Student reports are evaluated for mastery of the objective using a rubric.

Variation Tips

Students can create their own way to measure the strength of the electromagnet.  Suggested ideas include measuring the distance that the electromagnet can be separated from a paper clip and still attract or using weights instead of paper clips.

Students can also try to make the electromagnet as strong as they can by changing multiple factors while keeping a careful record of each individual change they make.

Students can also be allowed to choose their own factors to test.

Background and Preparation

Background / Preparation

1.  Students would need to be introduced to the parts of an electromagnet and the basic setup with a battery, wire, and nail.

2.  Materials needed for different groups of students to test different factors include but are not limited to:

  • different gauges(diameters) of wire
  • various sizes/voltages of batteries
  • nail-sized pieces of different metals
  • battery holders
  • wire cutters/strippers

Digital Tools / Resources

How an Electromagnet Works Video
https://www.youtube.com/watch?v=cxELqN7wjS0

Approved Date

Owner (Author)

hollyhevans
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