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Magnetis m Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic fields Magnetic Properties of Matter Magnetic Effects of a Current Please choose a topic Done By: Siddharth Arora The font used in this presentation is 1979 If your computer does not have this font it will display in Arial Sorry for the inconvenience caused

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Page 1: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetism

Laws of Magnetism

Magnetic Materials

Forces Between Magnets

Induced Magnetism

Methods of Magnetism

&

Demagnetization

Theory of magnetism

Magnetic fields

Magnetic Properties of

Matter

Magnetic Effects of a Current

Please choose a topicDone By: Siddharth

Arora

The font used in this presentation is 1979If your computer does not have this fontit will display in Arial Sorry for the inconvenience caused

Page 2: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Like poles _________

Unlike poles _______

1) repel; attract2) attract; repel3) explode; melt4) disintegrate; fly to the moon

Question 3

Question 2

Question 1

Instructions:

Click on the correct answer

Laws of magnetism

Page 3: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Which ones of the poles are North?

1) A,B2) none3) B,C4) B,D

Question 3

Question 2

Question 1

Instructions:

Click on the correct answer

Laws of magnetism

Page 4: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Instructions:

Click on the correct answer

Laws of magnetism

Magnetic North is geographical _______

1) South2) East3) Space time continuum 4) Centre of the Universe

Question 3

Question 2

Question 1

Page 5: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Laws of Magnetism• When a bar

magnet is suspended freely it always comes to rest in a north south direction.

Page 6: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Poles

• Magnetic South is geographical North.

• Magnetic North is geographical South

Page 7: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Poles

• Magnetic poles are located at the side of the magnets.

Page 8: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic & Non-Magnetic Materials

• Magnetic Materials include:– Iron– Cobalt– Nickel

• The rest are alloys of these metals such as steel.

Page 9: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Forces Between Magnets

• Like Poles Attract

• Unlike Poles Repel

Page 10: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Induced Magnetism

• A magnet attracts a non magnetic material by magnetic induction

Page 11: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods Of Magnetization

• Heating and Hammering– Place a steel bar in

the north-south direction and heat

– Hammer it while cooling

A magnet formed by this method is __________

A) Strong

B) Weak

Try This Question

Page 12: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods Of Magnetization

• Heating and Hammering– Place a steel bar in

the north-south direction and heat

– Hammer it while cooling

A magnet formed by this method is weak

Page 13: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods Of Magnetization

• Heating and Hammering– Place a steel bar in

the north-south direction and heat

– Hammer it while cooling

A magnet formed by this method is weak

Page 14: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization by stroking– Done as shown in

diagram

A magnet formed by this method is __________

A) StrongB) Weak

Try This Question

Page 15: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization by stroking– Done as shown in

diagram

A magnet formed by this method is weak

Page 16: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization by stroking– Done as shown in

diagram

A magnet formed by this method is weak

Page 17: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization using an electric current– A solenoid (a length of copper wire wound into

a long coil) is connected to a battery in series.– A iron bar is then placed inside the solenoid– The polarities depend no the direction of the

flow of the current

A magnet created in this way is ________

A) Strong

B) Weak

Try This Question

Page 18: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization using an electric current– A solenoid (a length of copper wire wound into

a long coil) is connected to a battery in series.– A iron bar is then placed inside the solenoid– The polarities depend no the direction of the

flow of the current

A magnet created in this way is strong

Page 19: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Methods of Magnetization

• Magnetization using an electric current– A solenoid (a length of copper wire wound into

a long coil) is connected to a battery in series.– A iron bar is then placed inside the solenoid– The polarities depend no the direction of the

flow of the current

A magnet created in this way is strong

Page 20: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Demagnetization

• A solenoid (a length of copper wire wound into a long coil) is connected to a battery providing alternating current.

• The magnet is then placed inside the solenoid• It is then removed in an East-West direction

Page 21: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Theory of Magnetism

• Magnetic domains (groups of small atomic magnets) are found in each magnet.

• A magnet is formed when all the domains point in one direction.

Page 22: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Fields

• The region around the magnet where its effects can be observed is a magnetic field

Page 23: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Fields

• Properties of magnetic fields– Outside the magnet

the lines start from the north pole and end at the south pole

– Inside the magnet they continue from the south pole to the north pole

Page 24: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Fields

– The lines never cross each other

– The lines behave as though they are pulled taut

– The lines repel each other

– Lines are close together in a stronger field than a weaker field

Page 25: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Fields

– The lines tend to pass through a magnetic substance

Page 26: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

• Soft Magnetic Materials– Easy to magnetize– Easy to

demagnetize– Can be used as

electromagnets– E.g.: Iron

Page 27: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

• Hard Magnetic Materials– Hard to magnetize– Hard to

demagnetize– Can be used as

permanent magnets

– E.g.: Steel

Page 28: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

• Permanent magnets– Magnetism is

retained for a long time

Page 29: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

• Electromagnets– Magnetic events

can only be observed for specific intervals of time

Page 30: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

• The strength of an electromagnet can be increased by:– Passing a larger

current through the solenoid

– Increasing the number of turns of the solenoid

Page 31: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

– Inserting a core of a soft magnetic material

A core of a hard magnetic material cannot be used because____________

A) It takes too long to magnetize and demagnetize

B) Its not cool

Try This Question

Page 32: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

– Inserting a core of a soft magnetic material

A core of a hard magnetic material cannot be used because It takes too long to magnetize and demagnetize

Page 33: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Properties of Matter

– Inserting a core of a soft magnetic material

A core of a hard magnetic material cannot be used because It takes too long to magnetize and demagnetize

Page 34: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Effect of a Current

• Magnetic effects of current means that a current flowing in a wire produces a magnetic field round it.

• As current increases more lines are formed

Page 35: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Effect of a Current

• Maxwell’s Corkscrew rule states that the direction of the magnetic field is the same as the direction in which you would turn an ordinary corkscrew to move it in the direction of the current.

Page 36: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Effect of a Current

• This can be interpreted as when current is flowing downwards or away from you, the magnetic field is in the clockwise direction

Page 37: Magnetism Laws of Magnetism Magnetic Materials Forces Between Magnets Induced Magnetism Methods of Magnetism & Demagnetization Theory of magnetism Magnetic

Magnetic Effect of a Current

• The magnetic field when the wire is in the shape of a flat coil or a solenoid, is shown in the diagram