MAGNETISM AND ELECTROMAGNETISM

magnetic field

Any charged particle in motion creates a

moving particle

induces a magnetic field in a plane perpendicular motion

closed loops

The lines of a magnetic field are always

magnetic dipole

* is the limit of either a closed loop of electric current or a pair of poles as the size of the source is reduced to zero while keeping the magnetic moment constant.
* small magnet created by the electron orbit
* a dipole with opposing magnetic poles

dipole

a pair of equal and opposite electric charges or magnetic poles separated by a small distance.

Magnetic Domain

* is a region within a magnetic material in which the magnetization is in a uniform direction.
* An accumulation of many atomic magnets with their dipoles aligned
* Rotation of orientation and increase in size of magnetic domains in response to an externally applied field.

Magnetic Permeability

• Is the ability of a material to attract the lines of magnetic field intensity

* Naturally occurring magnets


* Artificially induced permanent magnets
* electromagnets

Classification of Magnets

* Nonmagnetic
* Diamagnetic
* Ferromagnetic
* Paramagnetic

All matter can be classified according to the manner in which it interacts with an external magnetic field

Diamagnetic

tending to become magnetized in a direction at 180° to the applied magnetic field.

Ferromagnetic

– having a high susceptibility to magnetization, the strength of which depends on that of the applied magnetizing field, and which may persist after removal of the applied field. This is the kind of magnetism displayed by iron, and is associated with parallel magnetic alignment of neighboring atoms.

Paramagnetic

very weakly attracted by the poles of a magnet, but not retaining any permanent magnetism.

Magnetic Susceptibility

• The degree to which a material can be magnetized

* agnetic Laws
* Every magnet, no matter how small, has two poles: north and south.
* Like magnetic poles repel and unlike magnetic poles attract
* Ferromagnetic material can be made magnetic when placed in an external magnetic field.
* The force between poles is proportional to the product of the magnetic pole strengths divided by the square of the distance between them.

Magnetic Laws

tesla

The SI unit of magnet field strength is the

gauss

An older unit is the

10000 gauss (G)

One tesla (T) =

Electromagnetism

Is the force associated with electrons in motion

Solenoid

A coil of wire

Electromagnet

A ferromagnetic material wrapped in a coil of wire

* Alessandro Volta
* Hans Oersted
* Michael Faraday
* Heinrich Lenz

Pioneers in Electromagnetism

Faraday’s Law

Electric current will be induced to flow in a circuit if some part of that circuit is in changing magnetic field.

1. The strength of the magnetic field.
2. The velocity of the magnetic field as it moves past the conductor.
3. The angle of the conductor to the magnetic field.
4. The number of turns in the conductor.

The magnitude of the induced current depends on the following four factors:

Lenz’ Law

Induced current flows in a direction such that it opposes the action that induced it

1. Self-induction
2. Mutual induction

2 Types of Induction

Self-Induction

The induction of an opposing EMF in a single coil by its own changing magnetic field.

Mutual Induction

The process of inducing a current flow through a secondary coil.

* Electric Generator
* Electric Motor
* Transformers

Electromechanical Device and Electronic Devices

Electric Generator

* Changes mechanical energy into electrical energy
* a coil of wire is placed in a strong magnetic field between two poles of a magnet.

Electric Motor

* Changes electrical energy into mechanical energy.
* The same component but the source is electric no mechanical
* The electric energy is supplied to the current loop to produce a mechanical motion, that is, the rotation of the loop in the magnetic field.

Direct Current Motor

• Energy is supplied to a series of wire loops • DC motor is one type of motor that uses the DC current to convert electrical energy into mechanical energy. When the electric current passes through a coil in a magnetic field, a magnetic force will be generated which produces a torque in the DC motor

Induction Motor

• Energy is supplied to the external magnets