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Ferromagnetism: Hysteresis Loop

The document discusses several topics related to electromagnetism: 1) Ferromagnetism - Within ferromagnetic materials, atomic dipoles are arranged in domains that are randomly aligned, but an external magnetic field can force domain alignment. 2) Hysteresis loops - The relationship between magnetic field strength and magnetization in ferromagnetic materials involves hysteresis. 3) Electromagnetism - An electric current produces a magnetic field, and an electromagnet uses an iron core to concentrate magnetic field lines produced by a current. 4) The Hall effect - When a magnetic field is applied perpendicular to a current-carrying conductor, it exerts a force on charges, causing a voltage difference known

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Philip Moore
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36 views3 pages

Ferromagnetism: Hysteresis Loop

The document discusses several topics related to electromagnetism: 1) Ferromagnetism - Within ferromagnetic materials, atomic dipoles are arranged in domains that are randomly aligned, but an external magnetic field can force domain alignment. 2) Hysteresis loops - The relationship between magnetic field strength and magnetization in ferromagnetic materials involves hysteresis. 3) Electromagnetism - An electric current produces a magnetic field, and an electromagnet uses an iron core to concentrate magnetic field lines produced by a current. 4) The Hall effect - When a magnetic field is applied perpendicular to a current-carrying conductor, it exerts a force on charges, causing a voltage difference known

Uploaded by

Philip Moore
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF, TXT or read online on Scribd
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Ferromagnetism

Non-magnetised ferromagnetic material will have its dipoles arranged in groups called
domains. Within the domains, the dipoles are all parallel. However, the domains themselves
will be randomly aligned. When a piece of such material is placed inside of a solenoid (a
source of uniform magnetic field) the domains may be forced to align. When the external
field is removed, the domains will try to return to their original positions.

Hysteresis Loop

For more information check the following link:


https://www.nde-
ed.org/EducationResources/CommunityCollege/MagParticle/Physics/HysteresisLoop.htm
Electromagnetism
An electric current has an associated magnetic field. The direction of this field is determined
by the Right Hand Grip/Screw Rule. An electromagnet is then simply a magnet whose
magnetism depends on a flow of current. To produce an electromagnet, a material that retains
only a small amount of magnetism when the current is turned off, is required. (Thus
electromagnets are formed using ‘soft’ substances. ‘Soft’ simply means a material that is
easily magnetised/demagnetised. Iron and its derivatives are examples of a magnetically soft
metal. Nickel, steel and cobalt are examples of magnetically hard materials). Electromagnets
use iron as the core so that the core can be easily magnetised and demagnetised. This iron
core will increase the magnetic field strength of the electromagnet by:

 adding its own flux


 trapping the magnetic field lines in the core. The total flux,Φ, may be constant but by
varying the cross-sectional area of the core, then the magnetic field can also be varied.

Hall Effect
If a magnetic field is applied perpendicularly to a current carrying conductor, then a force
will be experienced by the charges carrying the current, due to the magnetic field.

This force will cause a build up of charge on one side of the conductor, leaving the other side
oppositely charged. Thus a potential difference will build up between the sides of a
conductor. This continues until it reaches a value called the Hall’s Voltage, VH. At this point
the magnetic force responsible for the build up of charge is equal to the force of repulsion the
charges experience as they build up.

Electric field is given by:

Recall electric force is given by:


When the Hall voltage is reached,
Hence:

v – drift velocity

A Hall Probe consists of a piece of semiconductor material which has a known current
passing through it. The probe is placed into a magnetic field and the Hall’s voltage is
measured. From this the magnetic field, B, can be determined.

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