"Magnetic Field" Magnetic Phenomenon PPT Courseware 3

Description

"Magnetic Field" Magnetic Phenomenon PPT Courseware 3

Review questions:

1. What is a magnet?

Answer: Magnetic objects.

2. What is magnetism?

Answer: Objects can attract the properties of three metal substances: iron, cobalt, and nickel.

3. What are the two strongest magnetic parts of a bar magnet called?

4. Interaction between magnetic poles?

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

Why do two magnets interact without touching each other when they are close to each other?

It shows that there must be a special invisible and intangible substance around the magnet. This substance is called a magnetic field in our physics.

Characteristics of magnetic fields: invisible and intangible, they do exist

think:

Since the magnetic field is invisible and intangible, how do we know it?

Comparative thinking:

In life, the flow of air forms wind. From what phenomena can we understand the existence of wind?

Answer: Know the direction of the wind from the leaves and flags, and know the strength of the wind from the amplitude of the swing.

Experiment 1: Put the magnet close to the small magnetic needle

1. What phenomena will we see? What does it mean?

Answer: You can see that the small magnetic needle deflects and points in different directions at different locations.

Explain the powerful effect of the magnetic field on the small magnetic needle.

2. What do the different directions of the small magnetic needles mean?

Answer: It shows that the magnetic field has direction. Explain that the directions of the magnetic field at various points around the magnet are different.

3. Regulation of magnetic field direction: When the small magnetic needle is stationary, the direction pointed by the N pole is the direction of the magnetic field at that point.

Magnetic field lines

In order to understand the magnetic field more intuitively, we introduce the concept of magnetic field lines. Through it we can know the direction and strength of the magnetic field.

Check out the experimental exploration below!

Explore experiments:

Sprinkle iron filings on a glass plate, place a magnet under the glass plate, and observe the pattern formed by the iron filings.

Magnetic field lines of bar magnet

Distribution rules of magnetic field lines:

It comes out from the N pole of the magnet and returns to the S pole.

The direction of the magnetic field at any point is consistent with the direction pointed by the north pole of the magnetic needle at that point.

Characteristics of magnetic field lines:

1. The magnetic field lines are closed curves. The magnetic field lines outside the magnet all come out from the N pole and return to the S pole. They go from the S pole to the N pole inside the magnet.

2. The direction of the magnetic field lines is the direction of the magnetic field, and it is also the direction pointed by the north pole of the small magnetic needle in the magnetic field.

3. Magnetic induction lines do not actually exist, they are assumed lines for the convenience of research; but magnetic fields exist objectively.

4. Magnetic field lines fill the entire space around the magnet. They also exist in places where magnetic field lines are not drawn, and the magnetic field lines will not intersect.

5. The closer the magnetic poles are, the denser the magnetic field lines are.

6. Magnetic field lines are distributed three-dimensionally, not just in one plane.

3. Geomagnetic field

After reading the textbook, answer the following questions:

1. What does the geomagnetic field resemble in shape?

bar magnet

2. What is the relationship between the direction of the geomagnetic field and the location of the geographical North and South Pole?

The magnetic poles of the geomagnetic field are near the geographical north and south poles and do not coincide with each other.

The geomagnetic south pole is near the geographical north pole, and the geomagnetic north pole is near the geographical south pole.

3． Who was the first scientist in my country to propose the existence of the geomagnetic field?

Shen Kuo

Geomagnetic field characteristics

The geomagnetic N pole is

Geographically near the South Pole;

The geomagnetic S pole is

Geographically near the North Pole.

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

Summary of research methods

1. Conversion method: In physics, for some invisible and intangible phenomena or physical quantities that are not easy to measure directly, we usually use some very intuitive phenomena to understand, or use easy-to-measure physical quantities to indirectly measure. This method of studying problems is called conversion method.

2. Modeling method: Things in reality are all intricate and complex. When using physical laws to study actual things, it is often necessary to simplify them as necessary and ignore secondary factors to highlight the main contradictions. Using this idealized method to simplify actual things, a series of physical models can be obtained. This method of researching problems is called modeling method.

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For more information about the "Magnetic Phenomenon and Magnetic Field" PPT courseware, please click on the Magnetic Phenomena ppt and Magnetic Field ppt tags.

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 4:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 4

New knowledge exploration

1. Electromagnet

Definition: An energized solenoid inserted into an iron core is called an electromagnet.

Working principle: Use the magnetic effect of electric current to work.

So the magnetic size of the electromagnet is related to...

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 3:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 3

Situation introduction

Are magnetism and electricity related?

magnet charged body

Can attract magnetic substances and attract light and small objects

There are North and South poles..

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 2:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 2

Review: What is observed when a small magnetic needle is placed around a bar magnet? What is the reason?

The small magnetic needle is observed to deflect.

Reason: Because there are magnetic fields around the magnet...

File Info

Update Time: 2024-09-09

This template belongs to Physics courseware Beijing Normal University Ninth Grade Physics Volume 2 industry PPT template

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