"Magnetic Field" Magnetic Phenomenon PPT Courseware 2

Description

"Magnetic Field" Magnetic Phenomenon PPT Courseware 2

1. Magnetic field lines

Magnetic field lines: A series of curves with arrows drawn in the magnetic field according to the direction of the N pole of the small magnetic needle.

Distribution of magnetic field lines

1. Magnetic field lines around a bar magnet

2. Magnetic field lines around the hoof-shaped magnet

3. Magnetic field between different magnetic poles

4. The magnetic field between the magnetic poles of the same name

Notice

1) The tangent direction at any point is consistent with the direction pointed by the N pole of the small magnetic needle at that point.

2) Outside the magnet, the magnetic field lines always originate from the N pole of the magnet and finally return to the S pole.

3) Where the magnetic field lines are distributed more densely, the magnetic field is stronger.

2. Geomagnetic field

The geographical poles do not coincide with the geomagnetic poles, and there is a magnetic declination. Shen Kuo, a famous scientist from the Song Dynasty in my country, was the first person in the world to accurately record this phenomenon. He clearly pointed out that the direction pointed by the compass "is often slightly east, not entirely south." This was more than 400 years before Columbus discovered this phenomenon when he crossed the Atlantic Ocean.

Si Nan

The Chinese nation has recognized the phenomenon of magnetism very early, and magnetism is a research field with a long history. The compass is one of the four great inventions of ancient China. Ancient China ranked first in the world in many fields such as the discovery, invention and application of magnetism. It can be said that China is the hometown of magnetism.

The compass is one of the four great inventions in ancient my country. In the 3rd century BC, during the Warring States Period, "Han Feizi" recorded: "The former king established Sinan to end the day and night." "Guiguzi" records: "When Zheng people take jade, they must carry it to Siman, so they are not confused."

The discovery of magnets, the discovery of magnets attracting iron, the invention of magnet guides and the earliest magnetic compasses (Sinan), the invention and application of compasses, the discovery of earth’s magnetic declination, the application of earth’s magnetic declination, the application of magnetism in medicine, The discovery of the Northern Lights, earth magnetic phenomena, sunspots, and solar magnetic phenomena were all discovered, invented, applied, and recorded in China first, or are at the forefront of the world. It can be said that China is the hometown of magnetism.

Class exercises

1. Regarding magnetic fields and magnetic field lines, which of the following statements is correct ( )

A. Magnetic field lines always point from the south pole of a magnet to the north pole

B． The direction of the magnetic field at each point on the same magnetic field line is the same

C. Where there are no magnetic field lines around a magnet, there is no magnetic field

D． The magnetic field exists objectively, and the magnetic induction lines do not exist objectively, but it can vividly describe the distribution, direction and strength of the magnetic field.

2. As shown in the figure, if the N pole of the bar magnet is brought close to a soft iron rod that is not originally magnetic, and the soft iron rod sucks up the iron filings below, then ( )

A. The upper end of the soft iron rod is the N pole and the lower end is the S pole.

B. The upper end of the soft iron rod is the S pole and the lower end is the N pole.

C. The entire soft iron rod is N pole

D. The entire soft iron rod is S pole

3. Point out the north and south poles of each small magnetic needle.

A left S right N, B left N right S, C left S right N, D left N right S

Summary of this lesson

1. Magnetic field lines

1. Definition: A series of curves with arrows drawn in the magnetic field according to the direction of the N pole of the small magnetic needle.

2. Rule: The tangent direction of any point is consistent with the direction pointed by the N pole of the small magnetic needle at that point.

Outside the magnet, the magnetic field lines always originate from the N pole of the magnet and return to the S pole.

Where the magnetic field lines are more densely distributed, the magnetic field is stronger.

2. Geomagnetic field

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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.

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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...

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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..

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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: 2024-10-04

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

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