Interactive Java Tutorials
Choose from the list of Java tutorials below to learn about concepts, laws, tools and historical milestones associated with electricity and magnetism. Because they allow you to manipulate variables at your own speed and to visualize invisible forces, these virtual demonstrations can be better than the real thing. To view these tutorials, your web browser must have Java Virtual Machine installed and functioning properly. Download free Java software.
Alternating Current
Alternating current behaves differently, depending on what components are in a circuit.
Barkhausen Effect
The Barkhausen effect makes the concept of magnetic domains audible (if not exactly music to the ear).
Bullet Speed
This tutorial takes a shot at explaining how circuits can be used to measure things beyond the capacity of human senses.
Capacitor
A capacitor is similar to a battery in that both store electrical energy. But a capacitor can't actually produce new electrons; it only stores them.
Compasses in Magnetic Fields
Experiment with the compass in this tutorial to see how it responds to magnetic fields.
Current Flow
This tutorial illustrates how the flow of water through a system of pipes can be used to understand the flow of current through an electric circuit.
DC Motor
Electric motors turn electricity into motion by exploiting electromagnetic induction.
Deionization
The magnets here at the lab can generate massive amounts of heat. To cool them off, we need massive amounts of water. But first, we have to take the ions out.
Diamagnetism and Paramagnetism
Think iron, nickel and other "ferromagnetic" substances are the only ones with magnetic properties? In fact, everything reacts to magnetic fields in some way.
Electromagnetic Deflection in a Cathode Ray Tube, I
Discovering how cathode rays behave in a magnetic field was a big step forward for scientists trying to understand the mysterious phenomenon.
Electromagnetic Deflection in a Cathode Ray Tube, II
Many people interact with cathode ray tubes for part, if not most, of the day without having a clue how they work. Here's the inside scoop.
Electromagnetic Induction
In 1831, Michael Faraday carried out numerous experiments to prove that electricity could be generated from magnetism. He not only demonstrated electromagnetic induction, but also developed a good conception of the processes involved.
Electrostatic Repulsion in Van de Graaff Bubbles
A fun look at how Van de Graaff generators illustrate electrostatic forces.
EMF in Inductors
Electromotive Force (EMF) and its sidekick, back EMF, are interesting electromagnetic phenomena that aren't really forces at all.
Hall Effect
When a magnetic field is applied perpendicular to the flow of current, the field causes resistance in the current. This is the Lorentz force at work, and can be observed well in the Hall effect.
Heat Resistance
Heating a metal conductor makes it more difficult for electricity to flow through it. See why in this tutorial.
Ignition Coil
Ladies and gentlemen, start your engines and learn about the ignition coil, a type of step-up transformer key (no pun intended) to the operation of your car.
Induced Current
A current can be induced in a conducting loop if it is exposed to a changing magnetic field.
Inductive Pendulum
Get the swing of electromagnetic induction with this simple tutorial.
Inductive Reactance
Like resistance, reactance slows an electrical current down. Explained by Lenz's Law, this phenomenon occurs only in AC circuits.
Lissajous Figures on an Oscilloscope
This tutorial is a three-dimensional simulation of a cathode ray oscilloscope producing Lissajous figures as it compares sinusoidal voltages.
Lorentz Force
Learn the Lorentz force with the help of this tutorial, in which a wire fashioned into a pendulum moves inside a magnetic field.
Magnetic Domains
In ferromagnetic materials, smaller groups of atoms band together into areas called domains, in which all the electrons have the same magnetic orientation. That's why you can magnetize them. See how it works in this tutorial.
Magnetic Field Around a Wire, I
Whenever current travels through a conductor, a magnetic field is generated.
Magnetic Field Around a Wire, II
A handful of iron filings helps visualize the invisible magnetic field that circulates around a wire with a current running through it.
Magnetic Field of a Solenoid
You can create a stronger, more concentrated magnetic field by taking wire and forming it into a coil called a solenoid.
Magnetic Shunt
Magnetic shunts are often used to adjust the amount of flux in the magnetic circuits found in most electrical motors.
Mass Spectra
The mass spectrum of a material, deduced using a machine called a mass spectrometer, reveals how many isotopes of a given element are to be found in the material. See here what these spectra look like and how they are useful.
Oscillator
Oscillators are a type of circuit found in many types of electronic equipment, including clocks, radios and computers.
Parallel Wires
A pair of parallel wires serves to illustrate a principle that French Scienist André-Marie Ampère was the first to comprehend, back in 1820.
Right and Left Hand Rules
No fancy movement in this tutorial, but these rules come in very handy when trying to understand some of what’s going on in our other tutorials.
Thomson Effect
Turn up the heat on electricity and you'll learn a lesson about thermoelectric effects.
Transformers
Transformers are devices that transfer a voltage from one circuit to another circuit via induction.
Transmission Lines
Electricity goes through some ups and downs on its way from the power plant to your house. Here's how it works.
Arc Lamp
Invented decades before it could be used, the first type of electric light was so brilliant it was used for lighthouses and street lamps.
Audion
In 1906, American physicist Lee De Forest invented the Audion (or triode), building on John Fleming's discovery of the diode just a few years before.
Barlow's Wheel
English mathematician Peter Barlow devised an instrument in 1822 that built on advances from earlier in the century (including the invention the battery) to create a very early kind of electric motor.
Contracting Helix
This nifty device, a kind of precursor to the Slinky, demonstrates how parallel wires attract.
Daniell Cell
English chemist John Frederick Daniell came up with a twist on the simple voltaic cell that resulted in a longer-lasting source of power.
Electricity Meter
When electricity became available to the masses, utilities needed meters to record customer usage. This early 20th century model resembles many in use today.
Electrostatic Generator
Though simple by today's standards, the early electrostatic generators were a great milestone in humankind's understanding of electricity, allowing scientists to produce electricity so they could study it.
Faraday's Ice Pail
Out of a humble ice pail the great experimentalist Michael Faraday created a device to demonstrate key principles of attraction, repulsion and electrostatic induction.
Faraday Motor
Just a year after electromagnetism was discovered, the great scientific thinker Michael Faraday figured out how to turn it into motion.
Foucault's Disk
Léon Foucault, a French physicist much better known for his pendulum demonstrating the rotation of the Earth, also created in 1855 a device that illustrated how eddy currents work.
Galvanometer
This tutorial illustrates how a galvanometer, an instrument that detects and measures small amounts of current in an electrical circuit, works.
Kelvin Water Dropper
The legendary Lord Kelvin made electricity from water with this ingenious electrostatic generator.
Leyden Jar
These devices, though quite humble, represented a tremendous breakthrough in the history of electricity; they were the first capacitors, and as such were able to store electric charge.
Lodge's Experiment
Sir Oliver Lodge's experiment demonstrating the first tunable radio receiver was an important stepping stone on the path toward the invention of a practical radio.
Magnetic Core Memory
Magnetic core memory was developed in the late 1940s and 1950s, and remained the primary way in which early computers read, wrote and stored data until RAM came along in the 1970s.
Mirror Galvanometer
Invented by William Thomson (who later became Lord Kelvin for such clever acts as this), the mirror galvanometer was a useful instrument that played a key role in the history of the telegraph.
Ørsted's Compass
In 1820, Hans Christian Ørsted discovered the relationship between electricity and magnetism in this very simple experiment.
Pixii Machine
This “magneto-electric machine” was the first to turn motion into electricity.
Rheostat
After discovering the nature of electrical resistance, scientists devised instruments like this one to measure and control it.
Simple Electrical Cell
The simple voltaic (or galvanic) electrical cell is the most basic type of "wet" cell and demonstrates the fundamental chemistry behind batteries.
Torsion Balance
Early instruments used in investigations of electricity could do little more than detect the presence of a charge. Then, in the mid-1780s, Charles-Augustin de Coulomb introduced the torsion balance, which could measure it.
Van de Graaff Generator
Invented around 1930, the Van de Graaff generator is a popular tool for teaching the principles of electrostatics. Others just call it "that thing that makes your hair stand on end." See how it works here.
Voltaic Pile
Italian scientist Alessandro Volta was the first to recognize key principles of electrochemistry, and applied those principles to the creation of the first battery, a simple tool which came to be known as the voltaic pile.
Wheatstone Bridge
This circuit is most commonly used to determine the value of an unknown resistance to an electrical current.
Fourier Transform Ion Cyclotron Resonance (FT-ICR)
FT-ICR is a powerful type of mass spectrometry, co-invented by the Magnet Lab's Alan Marshall, particularly suited to identifying heavy molecules.
Guitar Pickup
Keith Richards and Eric Clapton owe their fame and fortune (in part) to electromagnetic induction.
Magnetic Resonance Imaging (MRI)
In MRI, magnetic fields and radio wave pulses combine to get a unique, and medically beneficial, response from your body's hydrogen atoms. Take a peek in this tutorial.
Mass Spectrometer (Single Sector)
Mass spectrometers are machines that give scientists a look at the composition and origin of a material by analyzing and quantifying its atoms and molecules. This tutorial shows how a single sector mass spectrometer works.
Mass Spectrometer (Dual Sector)
Mass spectrometers are machines that give scientists a look at the composition and origin of a material by analyzing and quantifying its atoms and molecules. This tutorial shows how a dual sector mass spectrometer works.
Microwaves
What makes those kernels pop inside your microwave? A whole lot of water interacting with a whole lot of high-frequency electromagnetic waves.
Tape Recorder
Two heads — or even three — are better than one when it comes to understanding how tape recorders exploit electromagnetic induction.
Contributors: Matthew Parry-Hill (programmer); Kristen Eliza Coyne (writer, editor); Adam Rainey (web design); Jesse Birch, Eric Hooper, Kevin John, Richard Ludlow, Adam Rainey (graphic artists).
