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This is a little
summary note on
electromagnets
BASIC PRINCIPLE
•When electricity flows in a
wire a magnetic field is
formed around the wire.
•The stronger the current
the stronger the magnetic
field will be.
•When a current stops
flowing there is no
magnetic field
HOW WE CAN MAKE A STRONGER
MAGNETIC EFFECT
•If we make a coil of wire called a
solenoid the combined effect of the
magnetic field around each wire results
in a bar magnet being created.
•The more coils the stronger the
combined magnetic field
MAKING AN
ELECTROMAGNET
•If we put a soft iron
core inside the
solenoid when a
current flows an
electromagnet is
formed
STRENGTH
INCREASES IF
IT HAS:
•More coils
•More
current
•A bigger
iron core
How it works
1. Current goes on
2. Electromagnet is
formed
3. Armature is pulled
towards the
magnet
4. This closes the
contacts
5. So the mains
circuit is complete
6. So the motor goes
on
Quick quiz to test yourself
1. How do you make an electromagnet?
2. What is a solenoid?
3. What will happen to the strength of an electromagnet if:
You add another battery?
You increase the number of coils around the iron core?
You used an aluminium core instead of a soft iron one?
You used a smaller iron core?
4. How would you design a fair test to test the effect of adding
more coils?http://www.
Need more revision?
Try these sites
beginner
http://www.bbc.co.uk/education/ks3bitesize/science/home
_menus/menu_physics.shtml
More advanced
http://www.bbc.co.uk/education/gcsebitesize/science_physics
/electricity_and_magnetism/index.shtml