# Magnetism.

## Presentation on theme: "Magnetism."— Presentation transcript:

Magnetism

What is magnetism? Magnetism is the force of attraction between magnets and magnetic objects.

Characteristics of Magnets
All magnets have a North and a South Pole. All magnets have a magnetic field around them. The magnetic field is a line of force running from the north-seeking pole to the south-seeking pole of the magnet.

Earth’s Poles In our planet we have the North and South Poles.
Earth acts like a giant magnet and is surrounded by a magnetic field. Earth’s magnetic field is what causes the needle of a compass to point in different directions and causes the poles of a magnet to point either North or South.

Attractive Magnets!!! The north and south poles of two magnets attract each other. They always need to be opposite poles to be attracted. The magnetic force pulls them together.

Magnets of the same pole will repel each other, either two north or two south poles.
NOT ATTRACTED

Magnets and electricity
Magnetic fields can be created with batteries, bolts and wire.

Magnets and Electricity
Electricity and magnetism are related: An electric current produces a magnetic field. A change in a magnetic field can produce an electric current.

Magnets and Electricity
The strength of an electromagnet can be increased by: Increasing the number of coils. Increasing the voltage of the current.

Magnets and Electricity
Electromagnets are used in every day life: In telephones, electric motors, generators, televisions, door bells. You can see a huge electromagnet in action in a junkyard. A crane holding the electromagnet can be used to pick up metal pieces when current flows through it. When the crane operator wants to drop the scrap, he or she will simply shut off the current to the electromagnet.

REVIEW

How many poles do magnets have?
Two poles: North and South

What happens when two magnets of different poles are put close together?
They ATTRACT each other

What happens when two magnets with same poles are put close together?
They REPEL each other

What is the area of a magnetic force called?
Field

Electric current creates a _____________ field.
magnetic

What do you make if you put together a closed circuit and wrap the wire around an iron bolt?
Electromagnet

How can you make an electromagnet stronger?
You can wrap the wire around the iron bolt more times.