Electrical Engineering Magnetism and Electromagnetism

Magnetism is a physical phenomenon produced by the motion of electric charge, which results in attractive and repulsive forces between objects. It is most commonly associated with materials that have magnetic properties, such as iron and nickel.

• Permanent Magnet: A material that produces a magnetic field without needing an external power source. It retains its magnetism for a long period.
• Electromagnet: A type of magnet whose magnetic field is produced by the flow of electric current. It can be turned on or off by controlling the current.

Magnetic flux (Φ) is a measure of the total magnetic field passing through a given area. It is defined as the product of the magnetic field (B) and the perpendicular area (A) it penetrates: $\Phi =B\times A$

Magnetic hysteresis refers to the lag between changes in magnetization (magnetic field strength) of a material and changes in the applied magnetic field. The hysteresis loop shows the relationship between the induced magnetic field (B) and the magnetizing force (H).

Faraday's Law states that a change in magnetic flux through a closed loop induces an electromotive force (EMF) in the wire forming the loop. The induced EMF (ε) is given by: ε=−dΦdt\varepsilon = -\frac{d\Phi}{dt}ε=−dtdΦ​ where $\Phi$ is the magnetic flux.

Lenz's Law states that the direction of the induced current (or EMF) in a closed loop is such that it opposes the change in magnetic flux that produced it. This law is a consequence of the conservation of energy

Magnetic Field Strength (H): A measure of the magnetizing force applied to a material, typically measured in amperes per meter (A/m).

Magnetic Flux Density (B): A measure of the magnetic field within a material, typically measured in teslas (T). It accounts for the material's permeability.

The right-hand rule is a mnemonic used to determine the direction of the magnetic field around a current-carrying conductor. Point your thumb in the direction of current flow, and the curl of your fingers shows the direction of the magnetic field lines around the conductor.

Eddy currents are circular currents induced in conductive materials when they are exposed to a changing magnetic field. These currents flow in closed loops within the material, creating their own magnetic fields that oppose the original change in flux, according to Lenz's Law.

An electric motor converts electrical energy into mechanical energy through the interaction of magnetic fields. In a typical DC motor, a current-carrying armature rotates within a magnetic field, experiencing a force (Lorentz force) that causes it to turn.