原版英语RAZ 教案P05-Magnetism (3).pdf

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1、www.readinga-MagnetismMagnetismA Reading AZ Level P Leveled BookWord Count:1,170Visit www.readinga- for thousands of books and materials.Written by Elizabeth AustinIllustrated by John KastnerLEVELED BOOK PWritten by Elizabeth AustinIllustrated by John KastnerMagnetismLevel P Leveled Book Learning AZ

2、Written by Elizabeth AustinIllustrated by John KastnerAll rights reserved.www.readinga-Photo Credits:Front cover,page 20:Erin Hogan/Photodisc/Getty Images;back cover,pages 3,4(top left),4(bottom center),4(bottom right),11,14,16:PhotoSpin;title page,page 6:Jovani Carlo Gorospe/123RF;pages 4(top cente

3、r),17:Amos Morgan/Photodisc/Getty Images;page 4(top right):Ryan McVay/Photodisc/Getty Images;page 4(bottom left):Photodisc;page 5:Steve Cole/Photodisc/Getty Images;page 7:Courtesy of NASA/JPL;page 9:Arthur S.Aubry/PhotoDisc/Getty Images;page 10:Learning A-Z;page 13:Richard Gross/Corbis;page 19:Dragu

4、ta/Dwww.readinga-MagnetismCorrelationLEVEL PM2828Fountas&PinnellReading RecoveryDRA34Table of ContentsIntroduction.4Magnetism and Magnets .5Magnetic Field.8How Are Magnets Made?.10Try This.12Magnetism and Electricity.13Using Magnetism .16Conclusion .20Glossary .21IntroductionLook around your home an

5、d try to find a magnet.A magnet is a metal object that sticks to other metals.You might have some magnets among your toys.There are probably magnets on your refrigerator.But did you know that there may be hundreds of magnets in your home?You cannot see most of them.But they are inside your televisio

6、n,telephone,and stereo.They are inside electric motors that power your blender and hair dryer.Computers are full of magnets.And all the electricity that runs these things comes from magnetism.Magnetism Level P34Table of ContentsIntroduction.4Magnetism and Magnets .5Magnetic Field.8How Are Magnets Ma

7、de?.10Try This.12Magnetism and Electricity.13Using Magnetism .16Conclusion .20Glossary .21IntroductionLook around your home and try to find a magnet.A magnet is a metal object that sticks to other metals.You might have some magnets among your toys.There are probably magnets on your refrigerator.But

8、did you know that there may be hundreds of magnets in your home?You cannot see most of them.But they are inside your television,telephone,and stereo.They are inside electric motors that power your blender and hair dryer.Computers are full of magnets.And all the electricity that runs these things com

9、es from magnetism.Magnetism Level P56Magnetism and MagnetsMagnetism is an invisible force.A force is anything that pushes,pulls,or moves an object.Magnetism is a special force that only pulls on some metals,such as iron.A magnet will not push or pull plastic or tin.Magnetism flows in one direction t

10、hrough a magnet,no matter what shape the magnet is.It flows in one end and out the other.The ends of a magnet are called magnetic poles.Every magnet has a north and a south pole.The force flows out the north pole and back in the south pole.You can use two magnets to feel magnetism flowing.The north

11、pole of one magnet will stick to the south pole of the other.Now,try to push the two north poles together.It feels almost like trying to connect two hoses that are both spraying water.The magnetic force pushes the north poles apart,because the magnetic forces are flowing against each other.Two north

12、 poles will always repel each other.So will two south poles.Magnetism Level P56Magnetism and MagnetsMagnetism is an invisible force.A force is anything that pushes,pulls,or moves an object.Magnetism is a special force that only pulls on some metals,such as iron.A magnet will not push or pull plastic

13、 or tin.Magnetism flows in one direction through a magnet,no matter what shape the magnet is.It flows in one end and out the other.The ends of a magnet are called magnetic poles.Every magnet has a north and a south pole.The force flows out the north pole and back in the south pole.You can use two ma

14、gnets to feel magnetism flowing.The north pole of one magnet will stick to the south pole of the other.Now,try to push the two north poles together.It feels almost like trying to connect two hoses that are both spraying water.The magnetic force pushes the north poles apart,because the magnetic force

15、s are flowing against each other.Two north poles will always repel each other.So will two south poles.Magnetism Level P78The Earths iron core is magnetic.The whole planet acts like a giant magnet.If you dangle a magnet by a string,one pole will point north and the other will point south.This is exac

16、tly how a compass works.This gave the north and south poles of a magnet their names.Magnetic FieldThe magnetic force flows out the north pole of the magnet.Then,it loops around outside the magnet and flows back in the south pole.Magnetism flows through space in lines of force.The invisible shape for

17、med by the lines of force around the magnet is called the magnetic field.Do You Know?Earths north and south magnetic poles are not quite at the true North and South Poles.The north magnetic pole is in northern Canada.The south magnetic pole is in the Pacific Ocean south of Australia.Since Earths cor

18、e moves around,the magnetic poles move,too.They can even flip completely around.If this happened today,your compass needle would point south!Magnetism Level P78The Earths iron core is magnetic.The whole planet acts like a giant magnet.If you dangle a magnet by a string,one pole will point north and

19、the other will point south.This is exactly how a compass works.This gave the north and south poles of a magnet their names.Magnetic FieldThe magnetic force flows out the north pole of the magnet.Then,it loops around outside the magnet and flows back in the south pole.Magnetism flows through space in

20、 lines of force.The invisible shape formed by the lines of force around the magnet is called the magnetic field.Do You Know?Earths north and south magnetic poles are not quite at the true North and South Poles.The north magnetic pole is in northern Canada.The south magnetic pole is in the Pacific Oc

21、ean south of Australia.Since Earths core moves around,the magnetic poles move,too.They can even flip completely around.If this happened today,your compass needle would point south!Magnetism Level P910Any iron or other magnets inside a magnetic field will be pulled toward the magnet.Stronger magnets

22、have more lines of force and larger magnetic fields.To see a magnetic field,place a magnet on a piece of paper.Sprinkle iron filings around the magnet.The filings will gather along the lines of force in the shape of the magnetic field.How Are Magnets Made?The first magnets were made of a natural roc

23、k called lodestone.People used pieces of lodestone in compasses.But they did not know how they worked.Every material is made of extremely tiny pieces called atoms.Most atoms spin.This spinning creates a tiny,tiny force.In most things,like rocks or plastic,the atoms spin every which way.The tiny forc

24、es never add up.But when something becomes magnetized,the atoms spin in the same direction.All the tiny forces add up to create a magnetic force.Eventually,people learned how to line up the atoms in some metals to create new magnets.Magnetism Level P910Any iron or other magnets inside a magnetic fie

25、ld will be pulled toward the magnet.Stronger magnets have more lines of force and larger magnetic fields.To see a magnetic field,place a magnet on a piece of paper.Sprinkle iron filings around the magnet.The filings will gather along the lines of force in the shape of the magnetic field.How Are Magn

26、ets Made?The first magnets were made of a natural rock called lodestone.People used pieces of lodestone in compasses.But they did not know how they worked.Every material is made of extremely tiny pieces called atoms.Most atoms spin.This spinning creates a tiny,tiny force.In most things,like rocks or

27、 plastic,the atoms spin every which way.The tiny forces never add up.But when something becomes magnetized,the atoms spin in the same direction.All the tiny forces add up to create a magnetic force.Eventually,people learned how to line up the atoms in some metals to create new magnets.Magnetism Leve

28、l P1112Some things,such as iron,become magnetized more easily than others.A piece of ordinary iron is placed inside a strong magnetic field.The magnetic force makes the iron atoms line up and spin in the same direction.This makes a new magnet.The more atoms that spin in the same direction,the strong

29、er the magnet becomes.Sometimes if you drop a magnet,some of the atoms get knocked out of line,and the magnet gets weaker.Make your own magnet!You will need a large iron nail,a strong magnet,and several paper clips.1 Hold the nail by one end and slide it across the magnet in one direction.Keep slidi

30、ng it over and over.The magnets lines of force will start to line up the atoms in the nail.2 After 20 to 30 times,touch the nail to the paper clips.Does the nail pick up the clips?How many can it pick up at once?Keep stroking the nail along the magnet to make the nails magnetic force stronger.See if

31、 you can pick up all the paper clips at once.Try ThisMagnetism Level P1112Some things,such as iron,become magnetized more easily than others.A piece of ordinary iron is placed inside a strong magnetic field.The magnetic force makes the iron atoms line up and spin in the same direction.This makes a n

32、ew magnet.The more atoms that spin in the same direction,the stronger the magnet becomes.Sometimes if you drop a magnet,some of the atoms get knocked out of line,and the magnet gets weaker.Make your own magnet!You will need a large iron nail,a strong magnet,and several paper clips.1 Hold the nail by

33、 one end and slide it across the magnet in one direction.Keep sliding it over and over.The magnets lines of force will start to line up the atoms in the nail.2 After 20 to 30 times,touch the nail to the paper clips.Does the nail pick up the clips?How many can it pick up at once?Keep stroking the nai

34、l along the magnet to make the nails magnetic force stronger.See if you can pick up all the paper clips at once.Try ThisMagnetism Level P1314Magnetism and ElectricityMagnetism and electricity are very closely related.Magnets can make electricity.And electricity creates magnetic fields.This is becaus

35、e both magnetism and electricity affect the way atoms spin.All the electricity you use comes from machines called generators.Generators make electricity by spinning magnets around coils of wire.The magnetism creates an electric current in the wire.The difficult part is getting the magnets spinning.P

36、ower plants use running water,wind,or steam from burning fuel to turn the magnets.electric currentturning magnetwirecoilGeneratorMagnetism Level P1314Magnetism and ElectricityMagnetism and electricity are very closely related.Magnets can make electricity.And electricity creates magnetic fields.This

37、is because both magnetism and electricity affect the way atoms spin.All the electricity you use comes from machines called generators.Generators make electricity by spinning magnets around coils of wire.The magnetism creates an electric current in the wire.The difficult part is getting the magnets s

38、pinning.Power plants use running water,wind,or steam from burning fuel to turn the magnets.electric currentturning magnetwirecoilGeneratorMagnetism Level P1516Electricity can create special magnets called electromagnets.A wire is wrapped around a regular piece of iron.Then an electric current from a

39、 battery or outlet flows through the wire.The electric current makes a magnetic field.This magnetizes the iron.But the iron only stays magnetized as long as the electricity is on.Using MagnetismThe earliest use of magnetism was the compass.A small,freely moving magnetic needle pointed to Earths magn

40、etic north pole.This helped guide travelers and explorers.Modern travelers still use compasses.Electricity comes from spinning magnets inside generators.And electric motors work like generators in reverse.They use electric current to spin magnets.The magnets are attached to fans,cutting blades,or wh

41、eels.This is how fans,blenders,and remote-control cars work.electric currentiron barwire coilElectromagnetMagnetism Level P1516Electricity can create special magnets called electromagnets.A wire is wrapped around a regular piece of iron.Then an electric current from a battery or outlet flows through

42、 the wire.The electric current makes a magnetic field.This magnetizes the iron.But the iron only stays magnetized as long as the electricity is on.Using MagnetismThe earliest use of magnetism was the compass.A small,freely moving magnetic needle pointed to Earths magnetic north pole.This helped guid

43、e travelers and explorers.Modern travelers still use compasses.Electricity comes from spinning magnets inside generators.And electric motors work like generators in reverse.They use electric current to spin magnets.The magnets are attached to fans,cutting blades,or wheels.This is how fans,blenders,a

44、nd remote-control cars work.electric currentiron barwire coilElectromagnetMagnetism Level P1718Magnets can also encode information,or store it in a special code.Cassette tapes,videotapes,computer disks,and credit cards all use strips of tiny magnets.The magnets are the size of grains of powder.There

45、 can be millions of magnets on one tape,disk,or credit card.Each tiny magnet points in its own direction.The different positions of the magnets create a code.Tape players,VCRs,and computers sense the tiny magnetic fields and read the code.Putting a credit card,tape,or disk near a powerful magnet can

46、 mess up or erase the code.Some high-speed trains run on electromagnets.The trains have powerful electromagnets on the bottom.The track also has powerful electromagnets.The two electromagnets face each other so that they repel each other.The magnetic force is so strong that it lifts the train off th

47、e track.The train floats above the track.It actually flies as it travels.This makes a fast,smooth ride.Magnetism Level P1718Magnets can also encode information,or store it in a special code.Cassette tapes,videotapes,computer disks,and credit cards all use strips of tiny magnets.The magnets are the s

48、ize of grains of powder.There can be millions of magnets on one tape,disk,or credit card.Each tiny magnet points in its own direction.The different positions of the magnets create a code.Tape players,VCRs,and computers sense the tiny magnetic fields and read the code.Putting a credit card,tape,or di

49、sk near a powerful magnet can mess up or erase the code.Some high-speed trains run on electromagnets.The trains have powerful electromagnets on the bottom.The track also has powerful electromagnets.The two electromagnets face each other so that they repel each other.The magnetic force is so strong t

50、hat it lifts the train off the track.The train floats above the track.It actually flies as it travels.This makes a fast,smooth ride.Magnetism Level P1920Special machines called MRIs can look inside a persons body.The person lies inside a tube cut right down the center of a very powerful magnet.The l