Magnetism Produced By An Electric Current Is Called

You flip a light switch. The bulb glows. You press a button on your car key fob. The doors open up. You plug in your phone. The battery icon lights up.

None of this happens by magic. It happens because a Danish physicist named Hans Christian Ørsted noticed a compass needle twitch near a wire in 1820 — and realized electricity and magnetism weren't separate forces at all.

The magnetism produced by an electric current is called electromagnetism. It's the reason the modern world works.

What Is Electromagnetism

At its core, electromagnetism is simple: moving electric charges create magnetic fields. Now, when electrons flow through a wire — that's electric current — they generate a circular magnetic field around that wire. The stronger the current, the stronger the field.

But here's where it gets interesting. The relationship goes both ways. A changing magnetic field also creates an electric current. This symmetry — electricity creates magnetism, magnetism creates electricity — is the foundation of almost every piece of technology you use daily.

The Right-Hand Rule

If you point your right thumb in the direction of conventional current flow (positive to negative), your curled fingers show the direction of the magnetic field lines wrapping around the wire. It's a handy visualization tool that engineers and students have used for nearly two centuries.

Electromagnets vs. Permanent Magnets

A permanent magnet — like the one on your fridge — is always magnetic. In real terms, cut the power, and the magnetism vanishes. An electromagnet is different. Its domains are aligned and locked in place. It's magnetic only* when current flows. This on-demand control is what makes electromagnets so useful in everything from junkyard cranes to MRI machines.

Why It Matters

Without electromagnetism, you're reading this by candlelight. No, seriously.

Every generator at every power plant on Earth works on electromagnetic induction. Day to day, steam spins a turbine, which spins a magnet inside coils of wire (or vice versa), and that changing magnetic field pushes electrons through the grid to your outlet. No electromagnetism, no grid.

Electric motors? So same principle in reverse. Current through coils creates magnetic fields that push against permanent magnets or other fields, producing rotation. Your washing machine, your car's starter, the fan in your laptop — all electromagnetic.

Then there's communication. Radio waves, Wi-Fi, Bluetooth, 5G — these are all electromagnetic waves propagating through space. Light itself is an electromagnetic wave. The entire electromagnetic spectrum, from gamma rays to radio waves, is the same phenomenon at different frequencies.

Medical imaging? MRI stands for Magnetic Resonance Imaging. Even so, it uses superconducting electromagnets to align hydrogen nuclei in your body, then reads the radio signals they emit as they relax. It's electromagnetism letting doctors see inside you without cutting you open.

How It Works

The Magnetic Field Around a Straight Wire

Current flows. The field strength drops off with distance from the wire — inversely proportional to the radius. A circular magnetic field forms. Double the distance, halve the field strength.

The formula: B = μ₀I / 2πr

Where B is magnetic field strength, μ₀ is the permeability of free space (a constant), I is current, and r is distance from the wire. Just know: more current equals more field. You don't need to memorize it. More distance equals less field.

Coils and Solenoids

Bend that wire into a loop. The field lines concentrate through the center. Bend it into many loops — a coil, or solenoid — and the fields add up. Inside a long solenoid, the field is nearly uniform and strong.

B = μ₀nI

Where n is turns per unit length. This is why electromagnets use coils. A few amps through hundreds of turns creates a field strong enough to lift a car.

Iron Cores

Wrap that coil around a piece of iron. That said, the iron's magnetic domains align with the coil's field, amplifying it dramatically — sometimes by a factor of hundreds or thousands. On the flip side, this is how you get the massive lifting magnets at scrap yards. The iron doesn't stay magnetized when the current stops (mostly), which is the whole point.

Electromagnetic Induction

This is the other half of the equation. On the flip side, a static magnet next to a wire does nothing. The key word is changing*. Michael Faraday figured it out in 1831: a changing* magnetic field induces an electromotive force (voltage) in a conductor. Move the magnet, or move the wire, or vary the current in a nearby coil — now you get voltage.

Continue exploring with our guides on how to find the pythagorean triple and what does the roman numeral c mean.

Faraday's Law: EMF = -N(ΔΦ/Δt)

The induced voltage equals the number of turns times the rate of change of magnetic flux. On top of that, the negative sign? In practice, that's Lenz's Law — the induced current creates a field that opposes* the change that created it. Nature resists change.

This principle gives us:

• Generators (mechanical energy → electrical)
• Transformers (change voltage levels)
• Induction cooktops (changing field heats the pan directly)
• Wireless charging (changing field in the pad induces current in your phone)

Self-Inductance

A coil resists changes in its own current. When you try to increase current, the expanding magnetic field induces a voltage opposing the increase. When you try to cut current, the collapsing field induces a voltage trying to keep it flowing. This is inductance, measured in henries.

It's why fluorescent lights need ballasts. It's why switching off a big motor can arc across the switch contacts. It's also why inductors smooth out ripple in power supplies.

Common Mistakes

Thinking Static Fields Induce Current

People see a magnet sitting next to a wire and expect voltage. The field must change*. Because of that, nothing happens. This trips up students constantly — and occasionally hobbyists trying to build "free energy" devices.

Confusing Magnetic Field with Magnetic Force

The field exists whether there's something to feel it or not. In real terms, the force only appears when a moving charge (or another magnet) interacts with the field. No moving charge, no magnetic force — even in a strong field.

Ignoring Lenz's Law Direction

The induced current always* opposes the change. Always. If your circuit design assumes the induced voltage helps the change, it's wrong. This shows up in relay flyback diodes, motor drive circuits, transformer inrush current — everywhere.

Assuming Iron Cores Work at All Frequencies

Iron amplifies low-frequency fields beautifully. At high frequencies (MHz and up), eddy currents in the iron cause massive losses. In practice, that's why RF inductors use ferrite or powdered iron — or air cores. Using a laminated steel transformer core at 100 kHz will get hot fast.

Overlooking Skin Effect

At high frequencies, current crowds toward the surface of a conductor. On the flip side, the effective resistance goes up. This matters for inductors, transformers, and transmission lines. A wire that's fine at 60 Hz might be terrible at 1 MHz.

Practical Tips

Building an Electromagnet

Use enameled magnet wire — thin insulation lets you pack more turns. Wind neatly; layers on top of layers work fine. Plus, a soft iron core (a large nail works for demos) multiplies the field. And power it with a current-limited supply or a resistor in series. Don't just hook it to a battery — the wire will melt.

Reducing Unwanted Inductance

Twist your power wires together. The fields from the outgoing and return currents

cancel each other out, minimizing the magnetic field that can interfere with nearby components. Use shielded cables for sensitive circuits or high-speed digital signals. Keep high-current and high-frequency traces short and wide to reduce inductance and skin effect losses. Practically speaking, when designing inductors or transformers, calculate the core material’s saturation point — pushing it too far will cause distortion and overheating. Which means always include a flyback diode across inductive loads like relays or motors to protect circuitry from voltage spikes. If you’re experimenting with wireless power transfer, remember that efficiency drops sharply with distance due to field leakage and coupling inefficiencies. Test your coils at the intended frequency — a inductor optimized for audio might fail spectacularly at radio frequencies. And finally, embrace the mess: magnetic fields leak through walls, interfere with compasses, and hum through speakers. Shielding isn’t optional in precision electronics. By respecting these principles, you’ll avoid common pitfalls and harness inductance safely — whether you’re building a simple motor, a power supply, or something far more exotic.