"Properties of Electromagnets" Magical Electromagnet PPT Courseware 2

Description

"Properties of Electromagnets" Magical Electromagnet PPT Courseware 2

Review questions

1. The experiment shown in the picture is called _______ experiment, which illustrates _______________; this phenomenon is called the magnetic effect of current

2. The magnetic field outside the energized solenoid is similar to the magnetic field of the _____ magnet. Its two ends are equivalent to _______________, and its polarity is related to ____________; their relationship can be determined by _________.

Electromagnet:

1. Structure:

An electromagnet is a solenoid with an iron core.

How electromagnets work

The magnetic effect of current and the magnetization of the iron core inserted into the energized solenoid are greatly enhanced.

Experimental exploration

Study the relationship between the magnetic strength of the electromagnet and the magnitude of the current:

Study the relationship between the magnetic properties of electromagnets and the number of coil turns:

Study the relationship between the magnetism of electromagnets and whether there is an iron core in the coil:

Compare in experiment:

1. When the appearance is the same and the number of turns of the coil is the same, the greater the current, the stronger the magnetism.

2. The appearance is the same. When the current is constant, the more turns the coil has, the stronger the magnetism will be.

3. Other factors must be that there is an iron core with strong magnetism.

1. The magnetism of the electromagnet can be changed:

Magnetism is generated when electricity is supplied and disappears when the current is cut off.

2. The magnetic force of the electromagnet can be changed:

Increasing the current can increase the magnetic force of the electromagnet;

Reducing the current reduces the magnetic force of the electromagnet.

Increasing the number of coil turns can increase the magnetic force of the electromagnet;

Reducing the number of turns in the coil reduces the magnetic force of the electromagnet.

3. The north and south directions of the electromagnet can be changed:

Changing the direction of the current can change the north and south directions of the electromagnet.

Changing the winding direction of the coil can change the north and south directions of the electromagnet.

Discussion question: What are the advantages of electromagnets compared with the permanent magnets studied before?

1. Whether the magnetism of the electromagnet is controlled by the on-off current

2. The magnetic strength of the electromagnet can be controlled by the size of the current or the number of turns of the coil.

3. The polarity change of the electromagnet can be controlled by the direction of the current

The powerful magnets of the maglev train are made of electromagnets, and the power of the train also comes from the attraction and repulsion of the electromagnets between the track and the front of the train.

Applications of electromagnets

Electromagnets are also used in generators, motors and electromagnetic relays

The water inlet and drain valves of fully automatic washing machines and the valves of induction flushers in bathrooms are also controlled by electromagnets.

Class exercises

1. Among the following equipment or equipment, the one that uses the thermal effect of current is ( ), and the one that uses the magnetic effect of current is ( ).

A. Electromagnet B. Incandescent lamp

C. Electric water heater D. Electromagnetic crane

E. Air switch F. Fuse

G. Electric bell H. Rice cooker

2. Which of the following practices cannot increase the magnetism of the solenoid: ( )

A. Increase the current in the coil.

B. Change the direction of current in the coil.

C. Insert the iron rod.

D. Increase the number of turns of the coil.

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"Properties of Electromagnets" Magical electromagnet PPT courseware:

"Properties of Electromagnets" Magical electromagnet PPT courseware review: Basic properties of permanent magnets: 1. It is magnetic and can absorb iron products; 2. It has a south and a north pole; the south pole is represented by the letter S, and the north pole is represented by the letter N3 .Opposites attract each other, and like poles repel each other. electromagnet...

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Update Time: 2024-10-05

This template belongs to science courseware People's Education Press Fourth Grade Science Volume 2 industry PPT template

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