Electromagnetic Induction Topic

Induced Currents and Forces

Concept 9 demos

Wooden frame with two vertical rods suspended from springs at the top crossbar, each passing through a copper-wound solenoid coil at the base, yellow position markers on the rods, and a polarity-reversal switch board mounted between the coils

Electromagnetically Coupled Harmonic Oscillators

Demonstrates electromagnetic coupling between two spring-mass oscillators via Faraday induction. Students observe energy transfer through induced currents, phase relationships that depend on coil wiring sense, and rapid electromagnetic damping when …

Hand holding a flexible coil between the poles of a large C-shaped permanent magnet on a wooden base, connected via BNC cable to an Agilent oscilloscope displaying induced voltage pulses

Flexible Coil and Magnet

A flexible coil between magnet poles produces voltage pulses visible on an oscilloscope through three methods: waving (translation), rotating, and compressing/extending the coil. Students see that any change in magnetic …

Overhead projection showing galvanometer face (2 mA DC, scale -2 to +2) with silhouettes of three coils visible to the right

Overhead Galvanometer with Coils

Three coils with different turn counts (30, 50, 90) are connected in series to an overhead galvanometer. Moving a bar magnet through each coil shows that induced EMF scales with, …

Eddy Currents

Concept 5 demos

Eddy current pendulum: solid copper plate (left) and slotted copper plate (right) hanging from rods on a horizontal crossbar, with two black radar magnets on the bench below

Eddy Current Pendulum 1

Solid and slotted conducting plates swing through magnetic fields simultaneously. The solid plate stops almost immediately due to eddy current damping; the slotted plate swings freely. A striking demonstration of …

Copper plank inclined on a wooden block, with a cylindrical magnet and stainless steel cylinder at the top and a clear plastic catch box at the bottom

Eddy Current Braking

Students observe Lenz's law in action: a rare-earth magnet rolls at constant (very slow) velocity down a copper ramp while a non-magnetic cylinder accelerates normally. A second configuration shows a …

Two copper tubes on a green surface — one with viewing holes drilled along its length — alongside a penny and a small gold-colored neodymium disk magnet

Eddy Currents: Copper Tube

A neodymium magnet falls slowly through a copper tube (~10 seconds for 61 cm) while pennies drop in under a second, dramatically demonstrating Lenz's law and eddy current braking.

Transformers

Concept 6 demos

Two demountable transformers on metal stands connected by wet strings draped between them, with coils on wooden bases and an illuminated light bulb on the right; chalkboard with generator equations behind

Wet String Transmission Line

Demonstrates why power lines use high voltage. Transformers step 110V up to ~4800V to transmit power through high-resistance wet strings, then step back down to light a bulb. Direct connection …

Assorted small inductors and transformers on green surface: toroidal coils, cylindrical inductors, E-core transformer, basket-weave coils, small circuit board, and various other components

Coils and Transformers

A collection of small commercial inductors and transformers for show-and-tell. Includes anti-theft stickers, projector circuit board, toroidal cores at various winding stages, basket-weave coils, and transformers with adjustable cores. Use …

Assembled dissectable transformer on wooden base: black iron core frame with two white Leybold 983 coil units mounted side by side, illuminated round light bulb on left, power strip below

Dissectable Transformer

Demonstrates transformer action using a dissectable iron core and two 250-turn coils. Students see that a light bulb glows at full brightness through electromagnetic induction alone — no direct electrical …

Motors and Generators

Concept 10 demos

Vintage demonstration motor on a wooden base with a red copper wire armature coil between wooden uprights, horseshoe-shaped iron yoke, and visible commutator assembly

Demonstration Motor, Permanent Magnet

A permanent-magnet DC motor with exposed components shows how a commutator reverses current direction each half-turn to maintain continuous rotation. Useful for explaining commutator operation and the force on current-carrying …

Simple motor: wire coil mounted on a coffee cup with a permanent magnet behind it, on a wooden base with wire contacts for a 9V battery

Simple Motor

A simple homemade DC motor demonstrates the force on a current-carrying conductor in a magnetic field . Students see electrical energy converted to rotational kinetic energy and learn why commutation …

Motor-generator board with large bronze flywheel spinning (motion blur visible), small light bulb glowing on top, switches and colored wiring on wooden base, connected to red-topped 12V battery

Motor-Generator

Students observe how a single electromagnetic machine functions as both a motor and a generator, demonstrating the reversibility of electromechanical energy conversion. The demo also illustrates electromagnetic braking via armature …