"Electromagnets and Their Applications" Magnetic Phenomenon PPT Courseware 5

Description

"Electromagnets and Their Applications" Magnetic Phenomenon PPT Courseware 5

Thinking Review

1. What is the difference between electromagnets and ordinary magnets?

2. How can the presence and strength of the magnetism of the electromagnet be controlled?

3. Why is the core of electromagnet made of soft iron? And not made of steel?

4. Why is the magnetism greatly enhanced after inserting the iron core?

How does an electromagnet work?

Electromagnet: An energized solenoid with an iron core.

advantage:

1. The magnetism of the electromagnet can be controlled by turning the current on and off.

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

3. The polarity of the magnetic pole can be changed by changing the direction of the current.

Applications of electromagnets

Working principle: Close the switch, current passes through the electromagnet, and the magnet generates magnetism to attract the elastic piece, causing the hammer to hit the iron bell to make a sound. At the same time, the circuit is disconnected, the electromagnet loses its magnetism, and the circuit is closed again due to the elasticity of the elastic piece. . The above process is repeated in cycles, and the electric bell continues to make sounds.

Working principle of electromagnetic concentrator

Working principle: Different minerals have different magnetic properties. A rotating circular electromagnet is used to attract these minerals. Because they receive different magnetic forces, minerals with different magnetic properties can be separated.

Improve ability

1. Experiments show that magnets can attract one-yuan coins. The correct explanation for this phenomenon is ( )

A. The coin must be made of iron because magnets can attract iron

B. The coin must be made of aluminum because the magnet can attract aluminum

C. The stronger the magnet is, the more types of substances it can attract.

D. Coins contain magnetic materials, which can be attracted after being magnetized.

2. As shown in the picture, an iron ball is hung under the spring balance. When the spring balance is gradually moved from left to right, the spring

The indication of the scale will be ( )

A. unchanged

B. Gradually decrease

C. Decrease first and then increase

D. First increase and then decrease

3. The function of the telephone receiver is ( )

A. Convert sound into changing current

B. Convert current directly into sound

C. Make the resistance of the carbon particles increase and decrease suddenly, thereby producing a changing current in the circuit.

D. Make the iron piece vibrate with the magnetic change of the coil and make a sound

4. The N and S poles of the energized solenoid are determined by ( )

A. The number of turns in the coil B. The intensity of the current in the coil

C. Is there an iron core in the coil?

D. Solenoid winding method and current direction in the coil

5. In order to enhance the magnetism of the energized solenoid, which of the following measures is invalid ( )

A. Increase the voltage across it B. Increase the number of turns of the solenoid

C. Insert the iron core into the coil D. Change the direction of the current

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For more information about the PPT courseware "Magnetic Phenomenon Electromagnet and Its Application", please click the Magnetic Phenomenon ppt Electromagnet and Its Application ppt tag.

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Update Time: 2024-07-23

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