What magnetism is
Magnetism is a field effect related to moving electric charge and the magnetic behavior of materials. A magnet has regions we call poles, and magnetic fields describe the influence around it.
Electric current creates magnetism
When current flows through a wire, it creates a magnetic field around the wire. If the wire is wound into a coil, the field becomes stronger and more useful.
A wire with current becomes magnetic. A changing magnetic field can create voltage. This two way relationship is the heart of electromagnetism.
Electromagnets
An electromagnet uses electric current to create a magnetic field. The field can often be turned on and off by controlling current. Adding an iron core can make the field stronger.
| Device | Main effect | Common use |
|---|---|---|
| Electromagnet | Current creates magnetic field | Relays locks cranes |
| Motor | Current and field create motion | Fans pumps vehicles tools |
| Generator | Motion and field create voltage | Power stations alternators turbines |
| Transformer | Changing field transfers energy | Voltage change in AC systems |
| Speaker | Changing current moves a coil | Sound production |
Electromagnetic induction
Induction happens when a changing magnetic field creates voltage in a conductor. Generators and transformers depend on this effect.
This formula describes induced voltage from changing magnetic flux. The sign shows that the induced effect opposes the change that creates it.
Motors and generators
A motor converts electrical energy into motion. A generator converts motion into electrical energy. Both use the connection between current and magnetic fields.
Electromagnetic waves
Changing electric and magnetic fields can travel through space as electromagnetic waves. Radio, microwaves, infrared light, visible light, ultraviolet, X rays, and gamma rays are all part of the electromagnetic spectrum.
Strong magnetic fields and high power electrical machines can be dangerous. Keep magnetic devices away from sensitive medical equipment and follow qualified safety guidance around industrial systems.
Frequently asked questions
Yes. Visible light is an electromagnetic wave. It is the part of the spectrum human eyes can detect.
Continue into the machines that use electromagnetism every day.