"Magnetic Field of Electric Current" Magnetic Phenomenon PPT Courseware 5

Description

"Magnetic Field of Electric Current" Magnetic Phenomenon PPT Courseware 5

Activity: Explore the magnetic field around a straight current-carrying wire

Historically, electricity and magnetism were initially thought to be unrelated things. Two famous physicists, Ampere and Coulomb, also thought so. What do you think?

1. Experimental equipment

2. Demonstration experiment

3. Describe what you saw

Analysis and conclusion:

What conclusions can you draw from the experimental phenomena?

Experiments have shown that there is a magnetic field around a current-carrying wire, and its direction is related to the direction of the current.

Take a guess: What magnet’s magnetic field might be similar to that of an energized solenoid?

design experiment:

1. How to prove it?

2. How to determine the direction of the magnetic field at each point around the energized solenoid?

Discussion: What conclusions can you draw from experimental observations? Why?

in conclusion:

1. The magnetic field outside the energized solenoid is the same as that of the bar magnet.

2. The direction of the magnetic field of the energized solenoid is related to the direction of the current.

Ampere's rule

The relationship between the magnetic pole properties at both ends of the energized solenoid and the direction of the current can be judged using Ampere's rule.

Hold the solenoid with your right hand and bend your four fingers in the same direction as the current in the solenoid. The direction pointed by your thumb is the N pole of the energized solenoid. In other words, it is the direction of the magnetic field inside the energized solenoid.

Judgment of magnetic poles of energized solenoid→Ampere’s rule

⑴ Stretch out your right hand, with your thumb and four fingers on the same plane, and your thumb and four fingers perpendicular to each other, hold the solenoid.

⑵The bending direction of the four fingers is consistent with the direction of the current in the solenoid.

The end pointed by the thumb is the N pole of the energized solenoid.

Improvement exercises:

1. Mark the N and S poles of the solenoid.

2. Mark the direction of the current in the solenoid.

3. Draw the winding method of the solenoid according to the conditions given in the figure.

Example: As shown in the figure, L is an electromagnet, and a strip of magnet is suspended above the electromagnet with a spring. When S is closed, the length of the spring will __________. If the sliding piece P of the rheostat moves to the right, the length of the spring will __________ (become longer, shorter, or unchanged).

When S is not connected, the elastic force of the spring and the gravity of the magnet are balanced. When S is closed, according to Ampere's rule, it can be determined that the upper end of the energized solenoid is the N pole and the lower end is the S pole. Since the poles of the same name repel each other, the spring will become shorter. If the sliding piece P of the varistor moves to the right, the resistance of the varistor in the circuit increases, the current intensity of the circuit decreases, the magnetism of the energized solenoid weakens, the repulsive force decreases, and the length of the spring increases.

practise:

1. As shown in the figure, there are two coils L1 and L2 on the smooth bracket. After closing the key S, the conditions of the two solenoids are:

A. Stay still

B. mutually exclusive

C. attract each other

D. Unsure

2. As shown in the figure, if the electric key S1 is closed, the magnetism of the electromagnet will be:

A. Enhance

B. weaken

C. unchanged

D. Unable to judge

5. Summary

1. Electricity and magnetism are related to each other. Electricity can generate magnetism, and there is a magnetic field around current-carrying wires.

2. The magnetic field of an energized solenoid is similar to that of a bar magnet.

3. The relationship between the magnetic pole properties at both ends of the energized solenoid and the direction of the current can be judged by the right-hand screw rule.

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For more information about the PPT courseware "Magnetic Phenomena and Current's Magnetic Field", please click on the Magnetic Phenomena ppt Current's Magnetic Field ppt tag.

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 4:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 4

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...

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 3:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 3

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..

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 2:

"Magnetic Field of Current" From Compass to Maglev Train PPT Courseware 2

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: 2024-10-08

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

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