"Starting from Permanent Magnets" Electromagnets and Automatic Control PPT Courseware 2

Description

"Starting from Permanent Magnets" Electromagnets and Automatic Control PPT Courseware 2

1. Magnet

1. The property of attracting iron, cobalt, nickel and other substances is called magnetism.

2. Magnetic objects are called magnets.

3. Classification of magnets:

Artificial magnets and natural magnets.

Temporary magnets and permanent magnets

Bar magnet, hoof magnet, small magnetic needle

experiment

Spread the iron filings evenly on the white paper, place the magnets flat on the iron filings, then lift the magnets out and observe the phenomenon.

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

Notice:

1. Don’t let the magnet get close to it.

2. Observe the direction of other students’ small magnetic needles.

The position of the small compass needle when it is at rest always points in the north-south direction.

The end of the small magnetic needle pointing north is called the North Pole (N pole).

The end of the small magnetic needle pointing south is called the South Pole (S pole).

2. Magnetic induction line

Drawing the arrangement of small magnetic needles in the magnetic field with some arrowed curves can describe the magnetic field conveniently and vividly. Such curves are called magnetic induction lines.

bar magnet hoof magnet

1. Magnetic induction lines are closed curves that do not exist and do not intersect.

2. The tangent direction of a certain point of the magnetic field line indicates the direction of the magnetic field at that point.

3. The direction the north pole points when the small magnetic needle is stationary is the direction of the magnetic field at this point.

4. The density of magnetic field lines indicates the strength of the magnetic field.

Feedback in class

1. The law of interaction between magnetic poles is: magnetic poles with the same name ________ each other; magnetic poles with different names ________ each other.

2. There are _________ around the magnet, and the magnet exerts force on the pin through _________.

3. Define the direction that _______ points when the small magnetic needle is stationary at a certain point in the magnetic field as the direction of the magnetic field at this point.

4. In physics, _____ is used to describe the magnetic field. The magnetic field lines outside the magnet all start from the ___ pole of the magnet and return to the ___ pole.

Practice in class

1. Cut a bar magnet into two halves. Each bar magnet cut must be ()

A. Two opposite magnetic poles B. Two N poles

C. Two S poles D. Magnetism disappears, no magnetism

2 Which of the following objects can maintain magnetism for a long time after being magnetized ( )

A. Copper wire B. Steel knife

C. Iron nail D. Carbon rod

3. Regarding the understanding of magnetic field, which of the following statements is incorrect ( )

A. The magnetic field is a special substance that exists objectively.

B. Magnetic field lines can vividly describe the strength and direction of the magnetic field. Each of its tangent directions is consistent with the direction pointed by the north pole of the small magnetic needle placed at that point.

C. If a small magnetic needle is placed at a certain point in the magnetic field, the direction of the magnetic force received by the small magnetic needle will be the direction of the magnetic field at that point.

D. In a space with a magnetic field, a magnetic field line can be drawn at any point.

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"Starting from Permanent Magnets" Electromagnets and Automatic Control PPT Courseware:

"Starting from Permanent Magnets" Electromagnets and Automatic Control PPT Courseware 1. Magnets: Objects with magnetic properties are called magnets. (1) Magnetism: The property of an object to attract iron, cobalt, nickel and other substances is called magnetism. (2) Magnet classification: temporary magnets and permanent magnets, artificial magnets..

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Update Time: 2024-11-25

This template belongs to Physics courseware Guangdong and Shanghai Edition Ninth Grade Physics Volume 2 industry PPT template

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