Electromagnets Basics

Study Notes

An electromagnet is a type of magnet that produces a magnetic field when an electric current flows through it.
Consists of a coil of wire wrapped around a core, typically made of iron or ferrite.
The magnetic field strength is proportional to the number of turns of the coil, the current flowing through it, and the permeability of the core.
Electromagnets can be turned on and off by controlling the electric current.
Applications:
- Lifting and moving heavy objects in industry
- Magnetic Resonance Imaging (MRI) machines
- Electric motors and generators

Magnetic induction is the process of generating an electric current in a conductor when it is placed in a changing magnetic field.
Faraday's law of induction: ε = -N(dΦ/dt), where ε is the electromotive force, N is the number of turns of the coil, and dΦ/dt is the rate of change of magnetic flux.
Lenz's law: the direction of the induced current is such that it opposes the change in the magnetic field.
Applications:
- Generators and alternators
- Transformers
- Induction cooktops

A magnetic field is a region around a magnet or electrical current where the magnetic force can be detected.
Magnetic field lines:
- Emerges from the north pole and enters the south pole of a magnet
- Continuous and closed loops
- Density of lines indicates strength of the magnetic field
Magnetic field strength (B) is measured in teslas (T) and is proportional to the magnetic field intensity (H) and the permeability of the material.
Applications:
- Magnetic Resonance Imaging (MRI) machines
- Magnetic storage devices (e.g. hard drives)
- Magnetic separation and sorting in industry

Electromagnets produce a magnetic field when an electric current flows through them.
They consist of a coil of wire wrapped around a core, typically made of iron or ferrite.
The magnetic field strength is proportional to the number of turns of the coil, the current flowing through it, and the permeability of the core.
Electromagnets can be turned on and off by controlling the electric current.
They are used in various applications, such as:
- Lifting and moving heavy objects in industry
- Magnetic Resonance Imaging (MRI) machines
- Electric motors and generators

Magnetic induction is the process of generating an electric current in a conductor when it is placed in a changing magnetic field.
Faraday's law of induction states that ε = -N(dΦ/dt), where ε is the electromotive force, N is the number of turns of the coil, and dΦ/dt is the rate of change of magnetic flux.
Lenz's law states that the direction of the induced current is such that it opposes the change in the magnetic field.
Applications of magnetic induction include:
- Generators and alternators
- Transformers
- Induction cooktops

A magnetic field is a region around a magnet or electrical current where the magnetic force can be detected.
Magnetic field lines emerge from the north pole and enter the south pole of a magnet, and they form continuous and closed loops.
The density of magnetic field lines indicates the strength of the magnetic field.
The magnetic field strength (B) is measured in teslas (T) and is proportional to the magnetic field intensity (H) and the permeability of the material.
Applications of magnetic fields include:
- Magnetic Resonance Imaging (MRI) machines
- Magnetic storage devices (e.g., hard drives)
- Magnetic separation and sorting in industry