Study Notes
Electromagnets are magnets created by electric current, which can be turned on and off, unlike permanent magnets. They are useful in various applications due to their adjustable strength.
- Lodestone — a naturally magnetic rock that attracts iron. Example: Lodestone was used by the Ancient Greeks to discover magnetism.
- Bar Magnet — a permanent magnet with constant magnetism. Example: Bar magnets have north and south poles that attract opposite poles and repel like poles.
- Magnetic Field — the area around a magnet where magnetic forces act. Example: Magnetic field lines show the direction of magnetic forces, from north to south.
- Electromagnet — a magnet created by electric current flowing through a coil. Example: Electromagnets can be turned on and off and are used in scrapyards to move metal.
- Induced Magnetism — temporary magnetism in materials within a magnetic field. Example: Iron becomes magnetized when placed near a magnet.
Exam Tips
Key Definitions to Remember
- Lodestone: A naturally magnetic rock.
- Bar Magnet: A permanent magnet with fixed poles.
- Magnetic Field: The area where magnetic forces act.
- Electromagnet: A magnet created by electric current.
Common Confusions
- Confusing permanent magnets with electromagnets.
- Misunderstanding the direction of magnetic field lines.
Typical Exam Questions
- What word best describes bar magnets? Permanent
- What do opposite poles do? Attract
- Specifically in which direction do the lines run in a field diagram? North to south
What Examiners Usually Test
- Understanding the difference between permanent magnets and electromagnets.
- Ability to explain how electromagnets work and their uses.