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magnetism:magnetism

Magnetism

INTRODUCTION FOR MAGNETS AND ELECTROMAGNETS

Metals like iron are attracted to magnets. Most metals however are not attracted to magnets, these include copper, silver, gold, magnesium, platinum, aluminium and more. They may however magnetize a small amount while placed in a magnetic field. Magnetism can attract magnetic objects or push them away. Magnets have a magnetic north pole and a magnetic south pole. If the same pole of two magnets are placed near each other they will away (repel), while if different poles are placed near each other they will pull together (attract). Magnetic objects must be inside the magnetic field to respond, which is why you may have to move a magnet closer for it to have an effect. When an electric current flows in a wire it creates a magnetic field around the wire. By winding the wire into a coil we can strengthen the magnetic field. Electromagnets are made from coils like this. The magnetic field around an electromagnet is just the same as the one around a bar magnet. It can be reversed by turning the battery around. Unlike bar magnets the magnetism of electromagnets can be turned on and off just by closing or opening the switch.

A magnet has 2 poles. The North Pole and the South Pole. The North Pole is red and the South Pole is blue.

Magnets can attract or repel other magnets. They do this without touching because the magnetic field from both magnets extend outwards from the magnet. The magnets attract when the poles are opposite and they repel when they are the poles are the same.

How to magnetise a piece of iron: You attach an electro magnet to the end of a piece of iron with crocodile clips, then you turn it on and your piece of iron is magnetic. This is because the electricity from the electro magnet gets transferred to the piece of iron. You can make the iron un magnetic by hitting it against a table, this is so the electric particles will separate from each other.

The affect a magnet has on a magnetic material

If a material is magnetic it gets attracted towards the magnet. Such magnetic materials include iron, nickel and cobalt.

The Effect of a Magnet on a Non-Magnetic Material:

A non-magnetic is an object is ignored by a magnet. Non-magnetic materials include wood, rubber and plastic.

The long curved lines shown along the magnet are the magnetic lines of force. They run from the North Pole to the South Pole. The space in which the lines of force are spread around a magnet is called the magnetic field. They attempt to form closed loops from pole to pole. They never intersect. They all have the same strength. The number of lines of force per unit area determines the strength of the magnetic field at that point.

7.

The Difference Between Electro-Magnets and Permanent Magnets. The difference between electro-magnets and permanent magnets is that electro-magnets can be changed. Their strength can be changed and they can be turned on and off. This makes electro-magnets much more useful than permanent magnets. But the electro-magnet can overheat sometimes. Electro Magnets can be used in a garbage heap, they can turn on a magnet to pick up all the metal and turn it off to drop it.

An electromagnet is usually made up of a large amount of turns by a wire. This is to create a magnetic field. The wires are usually made up of ferromagnetic material e.g. Iron

An experiment to investigate the strength of an electromagnet might be: Hypothesis: “If I increase the number of turns of the wire, the electromagnet will pick up more paper clips” List of equipment: • Iron Nail • Battery • Coil insulated wire • Wire • Crocodile clips • Paperclips Safety: What might go wrong? The nail might get too hot What damage or injure could be a result? Burn yourself or setting on fire How likely is this to happen? Not likely (If you’re sensible) What will you do to reduce the damage of injure? Be careful and listen to instructions Method: 1. Wear protective clothing and goggles 2. Don’t have too many volts 3. Don’t leave it on too long so it gets hot 4. Disconnect it so there are no electric shocks 5. Allow it cool before next use

magnetism/magnetism.txt · Last modified: 2016/05/19 14:16 by rheadi