Electricity & Magnetism
The same force that makes lightning crack across the sky also powers your phone and makes magnets stick to your fridge. Discover the electromagnetic force!
"Everything is made of atoms, and atoms have tiny particles with electric charge. Protons are positive, electrons are negative. Opposites attract, and likes repel. That's the fundamental rule of electricity — and it explains an enormous amount of what happens in the world!"
Electric charge is a fundamental property of matter. There are two types: positive (carried by protons) and negative (carried by electrons).
The basic rule is simple: opposite charges attract, like charges repel. This is called the electromagnetic force, and it's one of the four fundamental forces of nature.
When you rub a balloon on your hair, electrons transfer from your hair to the balloon. The balloon becomes negatively charged and your hair becomes positively charged — so they attract each other, and your hair stands up toward the balloon!
Electric current is the flow of electric charges (usually electrons) through a material. Metals are good conductors because their electrons can move freely. Rubber and plastic are insulators — their electrons are tightly bound and don't flow easily.
A single lightning bolt can carry about 1 billion volts and heat the air to 30,000°C — that's five times hotter than the surface of the Sun!
"Think of an electric circuit like a water park. The battery is like a pump that pushes water uphill. The wires are like water slides. The light bulb or motor is like a water wheel that uses the flowing water to do something useful. The water (electrons) flows in a complete loop!"
An electric circuit is a complete path that allows electric current to flow. Every circuit needs:
A power source (battery or generator) — provides the energy that pushes electrons through the circuit.
Conductors (wires) — pathways for electrons to travel through.
A load (light bulb, motor, speaker) — a device that uses the electrical energy to do something useful.
Voltage is the 'push' that drives electrons through the circuit (measured in volts). Current is the flow rate of electrons (measured in amperes). Resistance is how much the material opposes the flow (measured in ohms).
Ohm's Law ties these together: Voltage = Current × Resistance (V = IR). More voltage means more current. More resistance means less current.
The electricity in your home travels through wires at nearly the speed of light — but individual electrons actually move quite slowly, only about 0.1 mm per second!
"Here's the beautiful thing: electricity and magnetism are really the same force! A moving electric charge creates a magnetic field, and a changing magnetic field creates an electric current. They're two sides of the same coin — that's why we call it electromagnetism."
Magnetism is closely related to electricity. Every magnet has a north pole and a south pole. Like poles repel; opposite poles attract (just like electric charges!).
The deep connection: moving electric charges create magnetic fields. This is why an electric current flowing through a wire creates a magnetic field around it. Wrap the wire into a coil, and you've made an electromagnet — a magnet you can turn on and off!
The reverse is also true: a changing magnetic field creates an electric current. This is called electromagnetic induction, discovered by Michael Faraday. It's how generators work — spinning magnets near coils of wire generates the electricity that powers our world.
This beautiful symmetry between electricity and magnetism was unified by James Clerk Maxwell into four elegant equations that describe all electromagnetic phenomena. These equations also predicted that light itself is an electromagnetic wave!
The Earth itself is a giant magnet! Its magnetic field is created by swirling liquid iron in the outer core, and it protects us from harmful solar radiation.
Experiment & Discover
Play with the simulation below to see physics in action!
Ohm's Law Circuit
Adjust voltage and resistance to see how current and brightness change. V = I × R
Test Your Understanding
As Feynman said: "If you can't explain it simply, you don't understand it well enough."
You rub a balloon on your hair and it sticks to the wall. Why?
Where You'll See This
Physics isn't just in textbooks — it's everywhere around you!
Your phone charges through electromagnetic induction — a changing magnetic field in the charger creates current in your phone's battery
MRI machines use powerful magnets to create detailed images of the inside of your body
Electric motors in cars, fans, and washing machines all work by using electromagnetism to create rotation
Credit card strips and hard drives store data using tiny magnetic patterns