Фізика 9. Розв'язування задач за темою "Магнітне поле струму. Правило свердлика". Презентація 9 клас

Summary

This lesson focuses on solving problems related to the magnetic field generated by an electric current. It introduces the right-hand rule for determining the direction of magnetic field lines and discusses how a compass needle or a coil behaves in different current flow scenarios. Through a series of tasks, students are guided to understand magnetic field strength, pole interactions, and the application of various rules such as Ampère's law. The lesson concludes with homework assignments to reinforce the topic covered, ensuring students have a solid grasp before moving forward.

Takeaways

• 🔍 The lesson focuses on solving problems related to the magnetic field of current and the right-hand rule.
• 📋 Before starting the lesson, students should self-assess their understanding of the previous topic using a provided link.
• 🔄 The direction of the magnetic field is determined by the right-hand rule, depending on the direction of the current flow.
• 🧭 A compass needle will align with the magnetic field lines generated by the current. The needle’s direction will change if the current’s direction is reversed.
• 🧲 When a magnetic needle is placed on the opposite side of the conductor, the magnetic poles (north and south) will reverse.
• 💡 The strength of the magnetic field decreases with distance from the conductor. Points equally distant from the conductor have equal magnetic field strengths.
• ⚡ In a coil, the right-hand rule can help identify the north and south poles based on the current direction. Like poles repel, while opposite poles attract.
• 📏 The magnetic field is stronger at points closer to the conductor. When comparing multiple points, proximity determines the magnetic field’s strength.
• 🧮 When analyzing two coils with current, their interaction can be explained by Ampère's force law. Coils with like poles facing each other will repel.
• 📚 The homework assignment involves studying paragraph 3 and solving exercises that are similar to the problems discussed in the lesson.

Q & A

What is the main topic of the lesson?

The main topic of the lesson is solving tasks related to the magnetic field of an electric current.

What is the first step recommended before starting the lesson?

Before starting the lesson, it is recommended to do a self-check to ensure that the previous topic is well remembered.

What is the rule of thumb used to determine the direction of magnetic induction lines around a conductor with current?

The rule of thumb used is the right-hand rule for a conductor with current, which states that if you point your thumb in the direction of the current, your fingers will curl in the direction of the magnetic induction lines.

How does the direction of the magnetic field change if the direction of the current changes?

The direction of the magnetic field will be opposite if the direction of the current changes, as the magnetic field lines are determined by the direction of the current.

What happens when the current flows in a different direction in the wire?

When the current flows in a different direction, the magnetic field lines will also change direction, aligning with the new flow of the current.

What is the relationship between the distance from the conductor and the strength of the magnetic field?

The magnetic field is weaker the further away from the conductor, as the strength of the magnetic field decreases with distance.

How can you determine the direction of the magnetic field at point A compared to point B?

You can use the right-hand rule to determine the direction of the magnetic field. If the magnetic induction lines are arranged in a clockwise direction, and you twist a screw in the same direction with your right hand, the direction your thumb points away from the screw indicates the direction the magnetic field lines go into the screen.

What will happen to the compass needle if the current direction changes?

If the current direction changes, the compass needle will align itself with the new direction of the magnetic field lines, which will be opposite to the original direction.

How does the interaction between two electromagnets with currents depend on their magnetic poles?

The interaction between two electromagnets depends on their magnetic poles: like poles repel each other, while opposite poles attract each other.

What will be the effect on the dynamometer if a magnet is suspended above an electromagnet and the circuit is closed?

If a magnet is suspended above an electromagnet and the circuit is closed, the like poles will repel each other, causing the magnet to move upwards. This will result in the dynamometer showing a lower force as the weight of the magnet decreases.

How can you determine the poles of the electromagnet when the direction of the current is known?

You can determine the poles of the electromagnet by using the right-hand rule. If you grasp the electromagnet with your right hand such that your fingers point in the direction of the current, your thumb will point towards the north pole of the electromagnet.