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Magnets

Includes how to make magnets and electromagnets
by

Adam Jolly

on 12 March 2014

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Transcript of Magnets

Learning Objectives
Magnets
Making magnets
Learn about magnetic shielding
Types of magnets
How to make magnets and how to demagnetise
Starter
Magnetic shielding
Types of magnets
Electromagnets
Learning Objectives
How to make and increase the strength of an electromagnet
The magnetic field around a solenoid and where the poles are
There are three main types of magnets:
Permanent magnets
Temporary magnets
Electromagnets
Making a magnet
You will be making a magnet from a needle.
The Science
The Method
Inside magnetic materials there are millions of atoms, each of which acts like a tiny magnet. In a temporary magnet, all their poles point in different directions like this:
When a permanent magnet comes close, its magnetic field causes all of the small
DOMAINS
to line up like this:
When this happens all of the domains combine their magnetic fields to form one big one!
Plenary
Starter
Would it be useful to have a magnet which you could turn on and off? What would you use it for?
For Hinchley Wood by Mr Jolly
This means that the material with temporary magnetism can be attracted to a magnet.
BUT! It also means that it has the possibility to become magnetic!
You are going to MAGNETISE a material with a property of temporary magnetism!
Permanent magnets are always magnetic!
Temporary magnets act like magnets in a magnetic field. They lose this ability when you take them out of a magnetic field.
Electromagnets are made by coiling wire around an iron core. When a current flows through the wire, it creates a magnetic field.
Demagnetising
http://www.coolmagnetman.com/magindex.htm
Once you have made your magnet, you will need to DEMAGNETISE it.
In the back of your books
True or false?
1. You cannot block a magnetic field.
2. There are three types of magnets.
3. Inside a magnet there are millions of 'mini-magnets'.
4. Once you have made a magnet you cannot undo it.
Try and think of questions that have these words for answers!
a. All the domains line up
b. Iron, Nickel, Cobalt
c. Heat it or hit it
To do this you will need:
A magnet
A pin
You stroke the pin with the magnet in the same direction repeatedly. (about 20-30 times!). This should hopefully cause the pin to be magnetic!
How can you tell if it is magnetic?
To demagnetise a magnet that you have created there are two main methods.
Heat it
Hit it
What is an electromagnet?
How can I make one get stronger?
Investigation
Changing the strength of an electromagnet by varying the amount of coils
Hypothesis:
Prediction:
Either increase the current, or increase the number of coils
Electromagnetic
fields
Plenary
The magnetic field around an electromagnet (
solenoid
) is similar to that of a normal magnet.
The poles of an electromagnet are dependent on the direction of current through the turns of coils.
How could you find the poles?
Number of turns of coils
Electromagnets are made by coiling wire, sometimes around an iron core. When a current flows through the wire, it creates a magnetic field.
In the back of your books
True or false?
1. Electromagnets have no poles
2. Another name for an electromagnet is Solenoid
3. Increasing current or turns of coils increases the strength of an electromagnet
4. Electromagnets aren't very useful
5. To demagnetise something you can cool it down
6. Temporary magnets can be magnetised
7. Cobalt, iron and nickel are magnetic
8. The geographical North Pole is also Magnetic North
The End.
Number of paperclips picked up
Full transcript