Magnetism
Visão Geral
Pick up two fridge magnets and you can feel an invisible force pulling them together or pushing them apart, depending on which way round you hold them. That same force guides compass needles, locks cupboard doors, and even steers charged particles streaming from the Sun away from Earth's surface.
In this lesson you will learn which materials respond to magnets and why, how to distinguish permanent magnets from induced ones, and how to map the invisible field that surrounds every magnet using compasses and field-line diagrams. These ideas underpin the electromagnetism topics that follow, and Edexcel tests them regularly on both Paper 1 and Paper 2.
Objetivos
- Know that magnets repel and attract other magnets and attract magnetic substances
- Describe the properties of magnetically hard and soft materials
- Understand the term 'magnetic field line'
- Know that magnetism is induced in some materials when they are placed in a magnetic field
- Investigate the magnetic field pattern for a permanent bar magnet and between two bar magnets
- Describe how to use two permanent magnets to produce a uniform magnetic field pattern
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Nota de Aula
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- Which of the following is NOT a magnetic material? A) Iron B) Cobalt C) Copper D) Nickel Answer: C
- What happens when two north poles are brought close together? A) They attract B) They repel C) Nothing happens D) They become demagnetised Answer: B
- Magnetic field lines around a bar magnet point: A) From south to north outside the magnet B) From north to south outside the magnet C) From north to south inside the magnet D) In random directions Answer: B
- A uniform magnetic field is represented by field lines that are: A) Curved and close together B) Straight and getting further apart C) Parallel and equally spaced D) Circular and concentric Answer: C
- Which of the following is the only sure test that an object is a magnet? A) It attracts iron filings B) It is attracted to a known magnet C) It is repelled by a known magnet D) It sticks to a fridge door Answer: C
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Livros Recomendados
Para aprender mais, fontes abertas
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Secção do manual
Magnetic Fields, Field Lines, and Force
Summarize properties of magnets and describe how some nonmagnetic materials can become magnetized
"Physics: Magnetic Fields, Field Lines, and Force" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/physics/pages/20-1-magnetic-fields-field-lines-and-force. Access for free at https://openstax.org/books/physics/pages/1-introduction
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Secção do manual
Ferromagnets and Electromagnets
Only certain materials, such as iron, cobalt, nickel, and gadolinium, exhibit strong magnetic effects. Such materials are called ferromagnetic , after the Latin word for iron, ferrum . A group of materials made from the alloys of the rare earth elements are also used as strong and permanent magnets;
"College Physics: Ferromagnets and Electromagnets" by OpenStax, OpenStax, Rice University, licensed under CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Source: https://openstax.org/books/college-physics/pages/22-2-ferromagnets-and-electromagnets. Access for free at https://openstax.org/books/college-physics/pages/1-introduction
Publicados por outras organizações com licenças abertas e creditados como pedem. As ligações abrem os seus sites.
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