Applications of Electromagnetism

Active learning works for electromagnetism applications because students often struggle to connect abstract field and wave concepts to real devices. By analyzing technologies like MRI scanners and designing simple motors, students see how EM principles solve human problems, which builds both conceptual understanding and lasting memory.

• 9th Grade
• Physics
• 4 activities
• 30 min–40 min

Learning Objectives

1. Analyze how electromagnetic induction is applied in generators and transformers to transmit electricity.
2. Evaluate the role of magnetic fields and radio waves in medical imaging technologies like MRI.
3. Design a simple device, such as an electromagnet or a basic motor, demonstrating a core electromagnetic principle.
4. Compare and contrast the societal benefits and drawbacks of widespread electromagnetic technologies, such as wireless communication and medical devices.

Case Study Analysis

⏱ 35 min·Small Groups

Case Study Analysis: MRI vs. X-Ray

Provide groups with a one-page brief comparing the physics of MRI and X-ray imaging. Groups complete a two-column organizer identifying the EM principle involved, the wave or field type used, whether radiation is ionizing, and the tissues best imaged. Groups share findings and the class builds a comparative summary of when each technology is the better clinical choice.

Prepare & details

How do MRI machines use strong magnetic fields and radio waves to create images of the body?

Facilitation Tip: During the Gallery Walk, ask students to post one question on each station’s poster and respond to a peer’s question before rotating, ensuring accountability for reading others’ work.

Setup: Groups at tables with case materials

Materials: Case study packet (3-5 pages), Analysis framework worksheet, Presentation template

• Analyze
• Evaluate
• Create
• Decision-Making
• Self-Management

Project-Based Learning

⏱ 40 min·Pairs

Design Challenge: Simple EM Device

Challenge pairs to sketch a simple device using electromagnetic principles (examples: a magnetic door latch, a reed switch, a coil speaker, a simple solenoid actuator). They label the operating principle, identify the input and output energy forms, and estimate whether the device requires AC or DC. Pairs present their sketches in a rapid two-minute gallery walk.

Prepare & details

Design a simple device that utilizes electromagnetic principles.

Setup: Flexible workspace with access to materials and technology

Materials: Project brief with driving question, Planning template and timeline, Rubric with milestones, Presentation materials

• Apply
• Analyze
• Evaluate
• Create
• Self-Management
• Relationship Skills
• Decision-Making

Socratic Seminar

⏱ 30 min·Whole Class

Socratic Seminar: EM Technology and Society

Students review two short articles on electromagnetic technologies (one on wireless communication infrastructure, one on medical imaging access disparities) before class. The facilitator poses: 'Which EM technology has had the greatest positive societal impact, and what responsibilities come with it?' Students build a structured argument using evidence from physics and the readings.

Prepare & details

Evaluate the societal impact of electromagnetic technologies, from communication to medical imaging.

Setup: Chairs arranged in two concentric circles

Materials: Discussion question/prompt (projected), Observation rubric for outer circle

• Analyze
• Evaluate
• Create
• Social Awareness
• Relationship Skills

Gallery Walk

⏱ 30 min·Small Groups

Gallery Walk: EM Applications Map

Post seven stations around the room, each showing an application (MRI, wireless charging, electric motor, radio antenna, microwave oven, transformer, generator) with a brief description. Student groups annotate each station: which core EM principle applies, what the energy input and output are, and one way the application could fail if the underlying physics were not carefully engineered.

Prepare & details

How do MRI machines use strong magnetic fields and radio waves to create images of the body?

Setup: Wall space or tables arranged around room perimeter

Materials: Large paper/poster boards, Markers, Sticky notes for feedback

• Understand
• Apply
• Analyze
• Create
• Relationship Skills
• Social Awareness

Teaching This Topic

Teach applications by starting with the problem before introducing the science. For example, ask why an MRI can’t use X-rays before explaining magnetic resonance imaging. This reverses the common sequence and helps students value the science because they see how it solves a need. Avoid overwhelming students with complex equations early; instead, use proportional reasoning and conceptual models to build intuition.

What to Expect

Successful learning looks like students explaining how specific EM principles enable technologies rather than just naming the devices. They should critique trade-offs in design choices and articulate why some applications require certain EM behaviors over others, using evidence from their analyses.

Watch Out for These Misconceptions

Common Misconception

During Case Study Analysis: MRI vs. X-Ray, watch for students who conflate ionizing radiation with all electromagnetic imaging. Redirect by asking them to compare the energy and interaction mechanisms of X-rays versus radio waves with the hydrogen nuclei in tissue.

What to Teach Instead

In the case study packet, include a table where students must list the type of EM wave used, its energy range, and the mechanism of image formation for both MRI and X-ray. Require them to explain why ionizing radiation is unsuitable for MRI in their case study write-up.

Common Misconception

During Design Challenge: Simple EM Device, watch for students who assume wireless devices require physical connections in the air.

What to Teach Instead

During the challenge, provide a short reading on wave propagation and ask students to sketch the EM waves traveling from the device to the receiver, labeling frequency and amplitude changes. Have them present this sketch during their design review.

Common Misconception

During Socratic Seminar: EM Technology and Society, watch for students who overlook risks in EM technology adoption.

What to Teach Instead

Assign specific readings on 5G health debates and power-line EM fields before the seminar. During the discussion, require students to cite one risk and one benefit from these readings when making arguments about regulation.

Assessment Ideas

Exit Ticket

After Case Study Analysis: MRI vs. X-Ray, ask students to write a paragraph explaining which technology they would choose for imaging a knee injury and why, citing at least one specific EM principle from their analysis.

Discussion Prompt

During Socratic Seminar: EM Technology and Society, assess understanding by listening for students who connect their arguments to specific EM principles or trade-offs discussed in the Design Challenge or Gallery Walk.

Quick Check

After Gallery Walk: EM Applications Map, show students images of an electric motor, an MRI machine, and a radio antenna. Ask them to write one sentence for each device explaining the primary electromagnetic principle it utilizes and one sentence about a trade-off or limitation of that technology.

Extensions & Scaffolding

• Challenge: Ask students to research how microwave ovens use EM waves and present a 2-minute explanation of the physics behind heating food.
• Scaffolding: Provide sentence starters for the Design Challenge, such as "To make the motor spin, we need to create... which will cause..."
• Deeper exploration: Have students investigate how wireless charging pads use resonant inductive coupling and compare it to traditional inductive charging.

Key Vocabulary

Electromagnetic Induction	The production of an electromotive force (voltage) across an electrical conductor in a changing magnetic field. This is the principle behind electric generators.
Superconducting Magnet	A powerful magnet made from materials that have zero electrical resistance when cooled to very low temperatures, essential for creating the strong magnetic fields in MRI machines.
Radio Frequency (RF) Waves	A type of electromagnetic wave used in technologies like MRI and wireless communication. In MRI, they are used to excite atomic nuclei.
Electromagnet	A type of magnet in which the magnetic field is produced by an electric current. Electromagnets can be turned on or off, and their strength can be adjusted.