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Introduction

Magnetism is a fascinating aspect of physics, and it plays a crucial role in our everyday lives. In GCSE Physics, understanding permanent and induced magnetism is essential for various topics.

Key Concepts

• Permanent Magnets:
• Magnets that retain their magnetism even after being removed from a magnetic field.
• They are made of materials like iron, nickel, and cobalt.
• Induced Magnets:
• Materials that become magnetic only when placed in a magnetic field.
• These materials lose their magnetism once removed from the field.

Properties of Permanent Magnets

• Have two magnetic poles: north and south.
• Opposite poles attract each other, while like poles repel.
• Strength of a magnet is measured in teslas (T).
• Magnets can create magnetic fields, which exert a force on other magnets and moving charges.

How to Induce Magnetism

• Stroking: Rubbing a magnet over an iron bar repeatedly in the same direction.
• Electromagnet: Creating a magnetic field using an electric current passing through a coil of wire.

Common Mistakes to Avoid

• Assuming all metals are magnetic.
• Mixing up the north and south poles of a magnet.
• Thinking that magnets can only attract other magnets.

Practice Problems

• Problem 1:

A magnet has a strength of 0.5 T. Calculate the magnetic force on a charge of 2 C moving at a velocity of 5 m/s perpendicular to the magnetic field.

• Solution:

Force (F) = Charge (q) x Velocity (v) x Magnetic field strength (B)

F = 2 C x 5 m/s x 0.5 T

F = 5 N

Conclusion

Permanent and induced magnetism are fundamental concepts in GCSE Physics. By understanding these principles, you can develop a solid foundation for further studies in electricity and magnetism.

• Exam Tips:
• Practice drawing diagrams of magnetic fields.
• Remember the rules for attraction and repulsion between magnetic poles.
• Be able to apply formulas for magnetic force and field strength.
• FAQ:
• Q: What can weaken a permanent magnet?
• A: Heat, dropping, and strong electric fields.
• Q: How can I increase the strength of an electromagnet?
• A: Increase the current, number of coils, or use a ferromagnetic core.