Electromagnetic or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing magnetic field.
An electromagnet, meanwhile, is a magnet powered by an electric current.
Electricity itself has a magnetic force. And whilst this is present even in just a simple copper wire – and, as we said, in all of the miniscule measurements of electric charge across every atom and chemical bond – scientists have found ways of making that force much stronger.
Generally, electromagnets use coils of wire, with each coil winding around a piece of metal – usually iron. This particular thing is called a solenoid. When there is an electric current flowing through this wire, the magnetic field produced is centred on the magnetic core, the piece of metal at the centre of solenoid. These electromagnets are super strong – and, as soon as you turn off the electricity, the solenoid stops being magnetized.
So, yes, really an electromagnet is really just a really strong magnet. However, this particular combination of electricity and magnetism is incredibly useful. And one of its most important applications is in electromagnetic induction – the productive of electromotive force (emf or induced voltage) through the movement of a magnetic field and this magnetic fields produce electricity.
Applications of electromagnetic induction
The principles of electromagnetic induction are applied in many devices and systems, including:
- Current clamp
- Electric generators
- Electromagnetic forming
- Graphics tablet
- Hall effect meters
- Induction cooking
- Induction motors
- Induction sealing
- Induction welding
- Inductive charging
- Magnetic flow meters
- Mechanically powered flashlight
- Rowland ring
- Transcranial magnetic stimulation
- Wireless energy transfer
Discovery of electromagnetic induction
Michael Faraday is generally credited with the discovery of induction in 1831, and James Clerk Maxwell mathematically described it as Faraday’s law of induction. Lenz’s law describes the direction of the induced field. Faraday’s law was later generalized to become the Maxwell–Faraday equation, one of the four Maxwell equations in his theory of electromagnetism.
- Giancoli, Douglas C. (1998). Physics: Principles with Applications (Fifth ed.). pp. 623–624.
- Ulaby, Fawwaz (2007). Fundamentals of applied electromagnetics (5th ed.). Pearson:Prentice Hall. p. 255. ISBN 978-0-13-241326-8.