Magnetism Travis&Peter

7/31/2019 Magnetism Travis&Peter

1/14

Magnetism


2/14

Properties of magnets

1. Magnets attract objects of iron, cobalt and nickel.

2. The force of attraction of a magnet is greater at its poles

than in the middle.

3. Like poles of two magnets repel each other.

4. Opposite poles of two magnets attracts each other.5. If a bar magnet is suspended by a thread and if it is free to

rotate, its South Pole will move towards the North Pole of the

earth and vice versa.


3/14

Methods of Magnetisation

Stroking method

Electrical Method using a direct current


4/14

Stroking Method

Use a permanent magnet and stroke an unmagnetised steel bar

several times with the same pole. The unmagnetised steel bar

will then become magnetic.


5/14

Induced Magnetism

Apart from the magnets you see commonly made up of

magnetite(ore of tin)

there are other magnets made of iron,steel,etc to which

magnetism is induced by passing electricity. From this

electricity the molecules are arranged in specific manner. Thisphenomenon of inducing electricity through magnetic

materials is called induced magnetism.


6/14

Methods of Demagnetisation

Heating

Hammering

Electrical method using an alternating current


7/14

Heating

The atoms of the magnet vibrate vigorously when heated,

causing the magnetic domains to lose their alignment.


8/14

Hammering

Hammering alters the alignment of the magnetic domains

causing the magnet to lose its magnetism


9/14

Electrical method using an

alternating current An alternating current is an electric current which varies its

direction many times per second. The magnet is then slowly

withdrawn in the East-West direction with the alternating

current still flowing in the solenoid.


10/14

Magnetic Field Pattern


11/14

Plotting of magnetic field with a

compass The magnetic fields around a magnet can be drawn with a

plotting compass. The direction of the magnetic field at a

point is given by the direction in which the compass needle is

pointing at that point.


12/14

Difference between permanent and

temporary magnetsPermanent Magnet Temporary Magnet

1. have the magnetic properties even

if the external field is zero.

2. is seen on hard magnetic materials,

which fall in to the ferromagnetic

material family.3. are used in devices such as electric

motors and generators

1. have magnetic properties only in the

presence of an external magnetic field.

2. is seen in soft magnetic materials,

paramagnetic materials and

diamagnetic materials.3. are used in places such as cranes.


13/14

Sources

http://www.citycollegiate.com/chapter17_Xc.htm

http://wiki.answers.com/Q/What_is_induced_magnetism

http://cbse.questionpaper.in/Thread34540-CBSE-Question-

Paper-Pattern.aspx

http://www.differencebetween.com/difference-between-

permanent-and-vs-temporary-magnets/

Physics Textbook
http://www.citycollegiate.com/chapter17_Xc.htmhttp://wiki.answers.com/Q/What_is_induced_magnetismhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://www.differencebetween.com/difference-between-permanent-and-vs-temporary-magnets/http://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://cbse.questionpaper.in/Thread34540-CBSE-Question-Paper-Pattern.aspxhttp://wiki.answers.com/Q/What_is_induced_magnetismhttp://www.citycollegiate.com/chapter17_Xc.htm


14/14

Credits

Done By Peter And Travis

Documents

Magnetism Travis&Peter