"Electromagnet" Electromagnetic Phenomenon PPT Courseware

Description

"Electromagnet" Electromagnetic Phenomenon PPT Courseware

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 what factors are related to the magnetic size of electromagnets? Let’s explore it together.

2. How to make the electromagnet stronger

(1) Conjecture: The strength of the magnet may be related to the size of the current, the number of turns of the coil and the presence or absence of an iron core.

(2) Experimental equipment: power supply, switch, rheostat, wire, ammeter, pin, electromagnet

(3) Design circuit diagram:

(4) Experimental method: Control variable method

What is the relationship between the magnetic strength of an electromagnet and the magnitude of the current?

Invariant: number of coil turns, all have iron cores

Amount of change: the size of the current

Phenomenon: The greater the current, the more pins are attracted

What is the relationship between the magnetic strength of an electromagnet and the number of turns in the coil?

Invariant: The size of the current is inserted into the iron core

Amount of change: number of coil turns

Phenomenon: The more turns a coil has, the more pins it attracts

The factors that affect the magnetic strength of electromagnets are:

The size of the current: the greater the current, the stronger the magnetism of the electromagnet;

Number of turns of the coil: The more turns of the coil, the stronger the magnetism of the electromagnet;

With or without iron core: insert the iron core to enhance the magnetism of the electromagnet.

3. Advantages of electromagnets

(1) The magnetism of the electromagnet can be controlled: it is magnetic when the power is on, and non-magnetic when the power is off.

(2) The magnetic strength of the electromagnet can be controlled: the magnetic strength of the electromagnet can be changed by changing the size of the current.

(3) The direction of the magnetic pole of the electromagnet can be controlled: the magnetic pole of the electromagnet can be changed by changing the direction of the current.

summary

(1) Electromagnet: A solenoid with an iron core inserted inside is called an electromagnet.

(2) Working principle: It works based on the magnetic effect of current and the enhancement of the magnetic field after inserting an iron core into the energized solenoid.

(3) Features: The on and off of the current can control the presence or absence of magnetism; the direction of the current can change the polarity of the electromagnet's magnetic poles; the size of the current or the number of turns can control the strength of its magnetism.

Consolidation exercises

1. The magnetic strength of the energized solenoid is related to ____________, ____________ and ____________.

2. As shown in the figure, when the slider of the sliding rheostat moves to the right, the current in the circuit will ________ and the magnetism in the electromagnet will ________.

3. As shown in the picture, to make the electromagnet have the strongest magnetism, the correct connection method is ( )

A. S1 is connected to 1, S2 is connected to 3

B. S1 is connected to 1, S2 is connected to 4

C. S1 is connected to 2, S2 is connected to 4

D. S1 is connected to 2, S2 is connected to 3

1.Electromagnetic relay

(1) Structure of electromagnetic relay

(2) Working principle of electromagnetic relay

working principle

When the electromagnet is energized, it pulls the armature down to close the working circuit. When the electromagnet is powered off, it loses its magnetism, and the spring pulls up the armature, cutting off the working circuit.

Conclusion: An electromagnetic relay is a switch that uses electromagnets to control the on and off of the working circuit.

(3)The function of electromagnetic relay

A device that uses low voltage and weak current (control circuit) to control high voltage and strong current (working circuit).

Because of this, electromagnetic relays can:

remote control

automatic control

security alarm

summary

1. Structure of electromagnetic relay

2. Circuit of electromagnetic relay

(1) Control circuit: low-voltage power supply; switch; electromagnet

(2) Working circuit: high-voltage power supply; contacts; electrical appliances

3. The role of electromagnetic relay

A device that uses low voltage and weak current (control circuit) to control high voltage and strong current (working circuit).

4. The essence of electromagnetic relay

An electromagnetic relay is a switch that uses electromagnets to control a working circuit.

5. This can be achieved using electromagnetic relays

(1) Remote control;

(2) Automatic control;

(3) Security alarm...

Consolidation exercises

1. Electromagnetic relays can be used to indirectly control the working circuits of ________ and ________ using ________ and ________ circuits.

2. Electromagnetic relays are mainly composed of ________, ________, _______, and _______.

3. A speaker is a device that converts ________ into ________. It is mainly composed of fixed ________, ________ and __________.

4. When reading the instructions for use of audio or video tapes, there is often a warning: "Do not place near the speakers of a television or tape recorder." The reason is ( )

A. The sound emitted by the TV or tape recorder will destroy the sound, image, etc. on the audio tape or video tape.

B. An idiom used by merchants

C. The magnetism on audio tapes or video tapes will interfere with the normal operation of televisions or tape recorders.

D. Magnets on TV or tape recorder speakers will destroy the magnetism of audio or video tapes.

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Update Time: 2024-10-20

This template belongs to Physics courseware Lu Jiao Edition Ninth Grade Physics Volume 2 industry PPT template

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