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 Current goes on Electromagnet is formed Armature is pulled towards the magnet This closes the contacts So the mains circuit is complete So the motor goes on

Quick quiz to test yourself How do you make an electromagnet? What is a solenoid? 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? 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