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Magnets

LO: To know that magnetic materials are made of tiny magnets describe and investigate magnetising iron by stroking

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How do you know if a material is magnetic or not?

Which of the following are magnetic?.

Silver (Ag)Magnesium (M

g)

Gold (Au)

Iron (F

e)

Zinc(Zn)

Cobalt (Co) Nickel (Ni)

Copper (Cu)

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Al ZnAg

Cu

Au

Mg

Electromagnetism : Magnetic?

N

S

Fe

NiCo

Magnetism is a property of the atoms in iron (Fe), nickel (Ni) and cobalt (Co).

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Magnetism is a property of the atoms in iron, nickel and cobalt. Little groups of atoms act like tiny magnets. Each little group of atoms is called a domain.

A normal piece of iron does not seem to be magnetic, because all the domains are magnetised in different directions. They cancel each other out.

When a piece of iron is magnetised all the domains line up. They do not cancel each other out any more.

MAKING MAGNETS VIDEO

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Magnetising IronYou can magnetise a piece of iron by stroking it. You always have to stroke in the same direction so that all the domains line up. You can also magnetise a piece of iron by leaving it next to another magnet for a while. Eventually, the domains move around so they are lined up.

1. Record how many paper clips a iron nail can pick up?2. Stroke the iron nail with a magnet (in the same direction) 10 times.3. Repeat 20, 30, 40, and 50 times.4. Record your results in the table

Number of time iron strokes with magnet

Number of paper clips attracted

0

10

20

30

40

50

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Answer in full sentences1 Which materials can magnets be made from?2 What is special about the atoms in these materials?3 What is a domain?4 Why doesn’t a normal piece of iron act like a magnet?5 Describe two ways of making a magnet.. 6 Explain why heating a magnet can remove its

magnetism. (Hint: You will need to think what happens to atoms in any solid material when the material is heated.)

7 Why should you not drop magnets on the floor?

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T/Fa Magnets only attract magnetic materials. b Magnets can attract and repel other magnets. c Magnets repel non-magnetic materials. d Magnetism goes through paper. e Magnetism goes through iron. f The two ends of a magnet are called the east and the west poles. g If you put two north poles together, they attract or repel? h If you put two south poles together, they attract or repel? i If you put a north and a south pole together, they attract or

repel?

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Fill in the blanks• In an unmagnetised piece of iron, the molecular magnets (domain)are pointing in

________________________________________________________.• • In a piece of magnetized iron, domains point _____________________________________• ______________ can be easily magnetised or demagnetized.• Compared to iron, __________________cannot be easily magnetised or demagnetised .• When a material that can show magnetic properties, is attracted to the end of a magnet, it

also becomes a magnet and can attract magnetic materials to it. This process is called_______________________________________________________________..

• A magnetic material can be magnetized by _____________________ method or by ____________________________ method.

• A magnetized piece of iron can be demagnetized by ______________________, ____________________________.

• A steel bar placed inside the coil for a short while becomes _______________________. • The polarities of the magnet depend on the direction of current flow.• An elecrtomaget is ________________________ than the magnet produced by stroking.