"What is Magnetism" From Compass to Maglev Train PPT Courseware 3

Description

"What is Magnetism" From Compass to Maglev Train PPT Courseware 3

New knowledge exploration

1. Magnetic phenomena

1. Magnets and magnetism

Design experiment verification:

Conclusion 1: Magnets can attract iron, cobalt, nickel and objects containing these substances.

Magnetism: Magnets have the property of attracting iron, cobalt, and nickel.

Magnet: A magnetic object.

2. Magnetic pole

The magnetism of a magnet is strongest at the ends and weakest in the middle.

Pole: The most magnetic part of a magnet. Its location is at both ends of the magnet.

For a magnet that can rotate freely, the magnetic pole that points to the north when it is stationary is called the south pole or S pole, and the magnetic pole that points to the north is called the north pole or N pole.

3. Interaction between magnetic poles

Question: Is there only attraction between magnets? What are the rules?

Equipment: Two bar magnets

Conclusion 4: Magnetic poles with the same name repel each other, while magnetic poles with different names attract each other.

4. Magnetization

How are artificial magnets made?

Some objects can acquire magnetism under certain conditions, a phenomenon called magnetization.

The magnetic pole pattern of a magnet after it is magnetized: the end of the iron piece close to the magnetic pole is the magnetic pole with the same name.

Applications of magnetic materials:

1), using the interaction between magnets.

2) Use the directivity of the magnet to point the direction.

3), magnetic recording

4), magnetic therapy for disease treatment and health care.

5. Magnetic field

Exploration Activity 1: What substances exist around the magnet?

Put the magnet close to the small magnetic needle and observe the phenomenon

Phenomenon: the small magnetic needle rotates

Thinking about the small magnetic needle rotating, what is the effect?

The magnet and the small magnetic needle are not in contact. How does it exert force on the small magnetic needle?

There is an invisible and intangible substance around the magnet that can deflect the pointer. This substance is called a magnetic field.

Characteristics of the magnetic field: invisible and intangible, but it is real

The basic properties of a magnetic field: the effect of producing a magnetic force on a magnet placed in it

5. Magnetic induction lines

Exploration Activity 3: How to describe the magnetic field vividly

We use some curves with arrows to draw the arrangement of small magnetic needles in the magnetic field. Such curves are called magnetic flux lines.

Magnetic field lines can conveniently and vividly describe the magnetic field

Characteristics of magnetic field lines

1. The direction of the magnetic field lines at a certain point in the magnetic field is consistent with the direction of the N pole of the small magnetic needle at that point.

2. The magnetic field lines outside the magnet start from the N pole of the magnet and return to the S pole.

3. The magnetic field lines are densest in the pole part of the magnet.

The density of magnetic field lines can indicate the strength of the magnetic field. The denser the magnetic field lines, the stronger the magnetic field.

6. Geomagnetic field

The rotation of the magnetic needle is the result of the action of the magnetic field. So compasses can guide north and south all over the world, but whose magnetic field is exerting the action?

1. The magnetic field that exists around the earth is called the geomagnetic field.

2. Studies have shown that the geomagnetic field has a shape similar to that of a bar magnet.

3. Geomagnetic field characteristics

The geomagnetic N pole is near the geographical South Pole;

The geomagnetic S pole is near the geographical North Pole.

The geographical poles are opposite to the geomagnetic poles and do not exactly coincide.

New knowledge exploration

1. Disconnect the strip magnet from the middle and get ()

A. A magnet with only N pole in one section and S pole in the other section

B. Both sections of iron are non-magnetic.

C. There are two magnets each with N pole and S pole.

D. A magnet with two sections whose magnetic poles cannot be determined

2. For the three steel blocks shown in the picture, the correct judgment is ( )

A. Both are magnets;

B． There are only two magnets;

C. It may be both magnets, or it may be only two magnets;

D． None of them are magnets.

3. As shown in the figure, a bar magnet has an S pole on the left end and an N pole on the right end. Which of the following images shows the change in magnetic strength from the S pole to the N pole is correct ( )

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"What is Magnetism" From Compass to Maglev Train PPT Courseware 2:

"What is Magnetism" From Compass to Maglev Train PPT Courseware 2 Know the properties of magnets: iron attraction and directivity. Be able to determine whether an object is magnetic and the magnetic poles of a magnet, and understand the concept of magnetization. Know that magnetic poles with the same name repel each other and magnetic poles with different names attract each other...

"What is Magnetism" From Compass to Maglev Train PPT Courseware:

"What is Magnetism" From Compass to Maglev Train PPT Courseware 1. The Magical Use of Magnetism 1. Basic knowledge of magnetism (1) Magnetic poles: the strongest magnetic part of the magnet. Any magnet has ______ magnetic poles, which are called ____________ (______). There are no magnetic poles with only single names..

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Update Time: 2024-10-20

This template belongs to Physics courseware Shanghai Science Edition Ninth Grade Physics industry PPT template

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