The best examples of real-world examples of magnetic fields and electrical circuits: 3 core examples and more

Three core real-world examples of magnetic fields and electrical circuits

Physics teachers love to say “electricity and magnetism are everywhere”, but that’s only helpful if you can point to specific, testable situations. Here are three core examples of real-world examples of magnetic fields and electrical circuits that map directly onto classic lab experiments.

1. Power transformers: coils, cores, and changing magnetic fields

Every time electricity is moved from a power plant to your home, transformers are quietly doing the heavy lifting. A transformer is a textbook example of a changing magnetic field interacting with electrical circuits.

On the primary coil, an alternating current (AC) creates a time-varying magnetic field in an iron core. That changing field threads the secondary coil, where Faraday’s law of induction kicks in and produces a voltage. Same physics as a simple lab transformer, just at thousands of volts and megawatts of power.

Real-world details:

• Where you see it: Gray boxes on utility poles, metal cabinets in neighborhoods, chargers for laptops and phones.
• Physics link: Faraday’s law (induced EMF), Ampère’s law (magnetic field from current), and energy conservation.
• Experiment tie-in: A bench-top transformer with adjustable turns ratio is a scaled-down version of the grid. You can measure how voltage and current change as the turns ratio changes.

For context on how transformers fit into the U.S. grid, the U.S. Energy Information Administration has an accessible overview of how electricity is delivered from plants to homes: https://www.eia.gov/energyexplained/electricity/delivery-to-consumers.php

2. Electric motors: turning current into motion

If you want a vivid example of real-world examples of magnetic fields and electrical circuits doing something tangible, look at any electric motor. From the fan in your laptop to industrial robots, motors turn electrical energy into mechanical rotation using magnetic fields.

When current flows through coils in the rotor or stator, it creates magnetic fields that interact with either permanent magnets or other electromagnets. The result is a torque that makes the rotor spin. In the lab, this connects directly to the classic experiment where a current-carrying wire in a magnetic field experiences a force (the Lorentz force).

Real-world details:

• Where you see it: Electric vehicles, washing machines, HVAC fans, power tools, drone propellers.
• Physics link: Lorentz force on moving charges, torque on current loops, magnetic dipoles.
• Experiment tie-in: A simple DC motor build (coil, magnet, battery, commutator) is a stripped-down version of what’s inside a Tesla or an industrial pump.

The U.S. Department of Energy has a clear primer on how electric motors work in the context of electric vehicles: https://www.energy.gov/eere/vehicles/articles/how-does-electric-car-motor-work

3. Generators: spinning coils to make electricity

If motors are about turning electricity into motion, generators do the reverse: they turn motion into electricity. This symmetry makes them one of the best examples of real-world examples of magnetic fields and electrical circuits for students trying to connect theory to power plants.

Inside a generator, a coil rotates in a magnetic field (or a magnet rotates near a fixed coil). As the coil cuts through magnetic field lines, the magnetic flux through the loop changes, inducing an alternating voltage. This is literally Faraday’s law in action on a national scale.

Real-world details:

• Where you see it: Power plants (coal, natural gas, nuclear, hydro, wind, geothermal), backup generators in hospitals, portable camping generators.
• Physics link: Faraday’s law, magnetic flux, sinusoidal AC waveforms.
• Experiment tie-in: A hand-crank generator in a lab is a direct, small-scale example of the same physics used in utility-scale turbines.

The U.S. Energy Information Administration explains how different power plants use turbines and generators to produce electricity: https://www.eia.gov/energyexplained/electricity/how-electricity-is-generated.php

More real examples of magnetic fields and electrical circuits in daily life

Once you see the pattern—currents create magnetic fields, changing fields induce currents—you start spotting examples everywhere. Here are more examples of real-world examples of magnetic fields and electrical circuits that go beyond the big three of transformers, motors, and generators.

Wireless charging and induction cooktops: near-field induction in your kitchen

Wireless phone chargers and induction cooktops are closely related. Both are based on the idea that a rapidly changing current in one coil can induce a current in another nearby conductor through a changing magnetic field.

• Wireless phone charging: The charging pad contains a transmitting coil driven by high-frequency AC. This creates an oscillating magnetic field. Your phone has a receiving coil; the changing field induces a voltage, which a circuit then rectifies and regulates to charge the battery.
• Induction cooktops: The cooktop contains a coil under the glass surface. High-frequency AC produces a changing magnetic field that penetrates the ferromagnetic pot. Eddy currents generated in the pot’s base heat it directly.

Physics connections:

• Time-varying magnetic fields
• Eddy currents and resistive heating
• Coupled oscillating circuits

These are among the best examples for explaining to non-physicists why “wireless power” is not magic—it’s just Maxwell’s equations in your kitchen.

MRI scanners: medical imaging with giant magnets and radiofrequency coils

Magnetic Resonance Imaging (MRI) is a high-tech example of real-world examples of magnetic fields and electrical circuits working at extreme scales. Hospitals use MRI scanners to create detailed images of soft tissue without X-rays.

Key components:

• Main magnet: A superconducting magnet creates a strong, uniform static magnetic field (often 1.5 to 3 tesla, thousands of times Earth’s field).
• Gradient coils: Additional coils produce controlled variations in the magnetic field to encode spatial information.
• RF coils: Radiofrequency (RF) coils act as both transmitters and receivers. They send RF pulses that tip nuclear spins and then detect the tiny induced voltages as the spins relax.

All of this is mediated by well-designed circuits and precisely controlled magnetic fields. For a medically focused overview, see the National Institute of Biomedical Imaging and Bioengineering (NIBIB) MRI page: https://www.nibib.nih.gov/science-education/science-topics/magnetic-resonance-imaging-mri

Hard drives and magnetic storage: bits as tiny magnetic domains

Before solid-state drives took over, spinning hard disk drives (HDDs) were the standard for data storage, and they’re still widely used in data centers. They offer a subtle example of magnetic fields and electrical circuits interacting at the nanoscale.

• Writing data: A write head is essentially a tiny electromagnet. When current flows through its coil, it creates a magnetic field that flips the orientation of microscopic magnetic domains on the disk surface.
• Reading data: A read head detects changes in magnetization as the disk spins underneath. Changes in magnetic field strength alter the resistance of the sensor (giant magnetoresistance or tunneling magnetoresistance), which the drive’s circuits convert into bits.

This is a clean example of how information can be encoded and read using nothing but magnetic fields and carefully engineered circuits.

Loudspeakers and headphones: turning signals into sound

Every time you listen to music through wired headphones or traditional speakers, you’re using another example of real-world examples of magnetic fields and electrical circuits.

Inside a dynamic speaker:

• An audio signal (AC current) flows through a voice coil.
• The coil sits in a static magnetic field produced by a permanent magnet.
• The varying current interacts with the magnetic field, producing a force that moves the coil back and forth.
• The attached diaphragm pushes and pulls air, creating sound waves.

This is the same Lorentz force principle you might study in a lab with a current-carrying wire in a magnetic field, just tuned for audio frequencies instead of abstract measurements.

Magnetic levitation trains: large-scale forces from controlled fields

Maglev trains are a dramatic, large-scale example of real-world examples of magnetic fields and electrical circuits. They use carefully controlled magnetic fields to levitate and propel train cars with minimal friction.

Two main concepts show up:

• Levitation: Superconducting magnets or electromagnets in the train interact with coils or magnets in the track to provide an upward force that balances gravity.
• Propulsion: Linear motors—essentially “unrolled” electric motors—use traveling magnetic fields along the track to pull or push the train forward.

The physics is the same as in motors and transformers, but stretched out over hundreds of feet of track and coordinated by power electronics and control circuits.

Credit cards, transit cards, and RFID: weak fields, big impact

Even your wallet is hiding examples of magnetic fields and electrical circuits.

• Magnetic stripe cards: The dark stripe on the back stores data in patterns of magnetized material. A card reader passes the stripe near a read head that detects changes in magnetic field as the card moves, inducing a signal.
• Contactless payment and transit cards (RFID/NFC): The reader generates a radiofrequency magnetic field. A coil in the card picks up energy from this field, powering a tiny circuit that communicates back using modulated signals.

These systems show how low-power, short-range magnetic fields can be harnessed for identification, access control, and payment.

Earth’s magnetic field and power-line interactions

If you want an example of magnetic fields at planetary scale interacting with our electrical infrastructure, look at geomagnetic storms.

During intense solar activity, changing magnetic fields in Earth’s magnetosphere induce currents in long conductors on the ground—especially power lines and pipelines. These geomagnetically induced currents (GICs) can overload transformers and disrupt grids.

This is a rare but very real example of real-world examples of magnetic fields and electrical circuits interacting without human design. The underlying physics is the same induction you study in the lab; the conductor just happens to be a continent-spanning power grid instead of a copper loop.

NASA and NOAA both track space weather and its impact on technology; NOAA’s Space Weather Prediction Center provides background and current alerts: https://www.swpc.noaa.gov

How to turn these real examples into lab experiments

If you’re working on a physics project or lab report, the best examples are the ones you can connect directly to measurements you can make yourself.

Some ideas:

• Use a coil and a bar magnet to model generator action, then compare your data to how large generators in power plants operate.
• Build a simple DC motor and relate its torque and speed to what you see in commercial motors in fans or toys.
• Wrap a coil around an iron core, drive it with AC, and measure induced voltage in a secondary coil to mirror power transformer behavior.
• Place a small metal disk above an AC-driven coil to observe eddy current heating, then connect it conceptually to induction cooktops.

When you describe your work, anchor it with phrases like “this setup is an example of the same physics used in…” and then reference one of the real examples of magnetic fields and electrical circuits from above. That connection tends to impress graders and makes your explanations much clearer.

FAQ: examples of magnetic fields and electrical circuits

Q: What are the best examples of real-world examples of magnetic fields and electrical circuits that I can mention in an exam answer?
Strong, widely recognized examples include power transformers, electric motors, generators in power plants, wireless phone chargers, MRI scanners, and loudspeakers. If you need just three core examples, transformers, motors, and generators cover most key concepts in electromagnetism.

Q: Can you give an example of a simple household device that uses both magnetic fields and circuits?
A kitchen blender is a clean example. It contains an electric motor where current in coils creates magnetic fields that interact with other fields to spin the blade. The control electronics manage the current and therefore the torque and speed.

Q: Are wireless chargers and induction cooktops based on the same physics?
Yes. Both rely on time-varying currents in a coil creating oscillating magnetic fields, which induce currents in another conductor. The difference is scale and frequency: wireless chargers aim for efficient power transfer to a small coil in your phone, while induction cooktops are optimized to generate strong eddy currents (and heat) in cookware.

Q: Do smartphones themselves provide examples of magnetic fields and electrical circuits?
They do. Inside a smartphone you’ll find small speakers and vibration motors, wireless charging coils (on many models), and magnetic sensors (magnetometers) for compass functionality. Each of these subsystems uses magnetic fields interacting with currents in carefully designed circuits.

Q: Is Earth’s magnetic field strong enough to affect everyday circuits?
For most small-scale circuits, Earth’s field is too weak to matter. However, at the scale of long-distance power lines and pipelines, changes in Earth’s magnetic environment during geomagnetic storms can induce large currents. That’s why grid operators pay attention to space weather forecasts.

These examples of real-world examples of magnetic fields and electrical circuits are not just trivia; they are a practical toolkit. If you can explain how transformers, motors, generators, wireless chargers, MRI scanners, and speakers use magnetic fields and currents, you’re in very good shape for any physics class or lab focused on electromagnetism.