Electromagnetism Made Simple: Electromagnet, Motor, and Generator

How are electricity and magnetism connected? Electromagnetism links both topics and leads to the most important devices in our daily life, from the electric motor to the power plant. This in-depth guide shows a clear path through the topic, with experiments, applications, and ready material.

Current makes magnetism

Oersted's experiment starts it off: a current-carrying wire deflects a compass needle, so every electric current is surrounded by a magnetic field. Wind the wire into a coil and add an iron core and you get an electromagnet. Its big advantage over a permanent magnet: you can switch it on and off and control its strength.

What the strength depends on

An electromagnet gets stronger with more current, more coil turns, and an iron core. These three factors are nicely investigated by experiment, for example by counting how many paper clips the magnet holds.

Applications of the electromagnet

• Doorbell: an electromagnet pulls a hammer that strikes a gong.
• Relay: a small current switches a large circuit.
• Lifting magnet: at a scrapyard it raises heavy iron and drops it at the push of a button.
• Loudspeaker: a coil in a magnetic field makes the cone vibrate.

From electromagnet to motor

A force acts on a current-carrying wire in a magnetic field. In an electric motor this force turns a rotatable coil between the poles of a magnet. A commutator switches the current at the right moment so the coil keeps turning. This converts electrical energy into motion, and motors are in countless devices.

Induction and generator

Move a magnet in a coil (or the coil in a field) and a voltage appears, this is electromagnetic induction. The motion is essential: if the magnet is still, no current flows. A generator uses exactly this: a coil turns in a magnetic field and produces current continuously. In a power plant, water, wind, or steam drives a turbine that turns the generator, so the electricity from the outlet is made. The generator is basically the reverse motor.

The through-line

Electromagnetism connects the two previous topics: electricity (circuits) and magnetism. Teaching the series in this order creates a satisfying arc, from the simple bulb to the question of how electricity is actually made.

Ready material

The complete unit includes a workbook, a jigsaw, picture cards, a slide deck, and an answer key:

• Electromagnetism: Electromagnet, Motor, Induction & Generator
• Part of the Electricity & Magnetism bundle (12 lessons)

Frequently asked questions

How do you strengthen an electromagnet? More current, more turns, and an iron core.

What is the difference between motor and generator? The motor turns current into motion, the generator turns motion into current, the reverse motor.

Do you need expensive gear? A simple motor and generator set is enough for impressive experiments.

When does induction make a current? Only when magnet and coil move relative to each other.

What drives a turbine in a power plant? Water, wind, or steam, a good prompt to discuss energy sources.

How do you secure understanding? Through energy arrow diagrams (electrical to motion and back) and the picture cards.