Magnets and Magnetic FieldsAQA GCSE Physics: Flashcards
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What is a magnetic field?
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- What is a magnetic field?
- The region around a magnet where a force acts on another magnet or on a magnetic material.
- Name four magnetic materials.
- Iron, steel, cobalt and nickel.
- What happens between like poles? Between unlike poles?
- Like poles (N-N or S-S) repel; unlike poles (N-S) attract.
- Is the magnetic force a contact or non-contact force?
- A non-contact force — it acts without the magnets touching.
- How does field strength vary with distance from a magnet?
- It is strongest at the poles and gets weaker further away.
- How is the direction of a magnetic field at a point defined?
- As the direction of the force that would act on a north pole placed at that point.
- What is a permanent magnet?
- A magnet that produces its own magnetic field at all times.
- What is an induced magnet?
- A material that becomes magnetic only when placed in a magnetic field.
- Does an induced magnet ever repel the magnet inducing it?
- No — an induced magnet always experiences a force of attraction, never repulsion.
- What happens to an induced magnet's magnetism when it is removed from the field?
- It loses its magnetism quickly.
- What instrument is used to plot a magnetic field pattern, and how?
- A plotting compass; you mark the direction it points, move it to that point, and repeat, joining the marks to trace a field line.
- In which direction do field lines run around a bar magnet?
- From the north pole, curving round through the space outside the magnet, into the south pole.
- What does it mean if field lines are drawn closer together?
- The magnetic field is stronger in that region.
- Why does a compass needle point north-south?
- Because the Earth's core behaves like a giant magnet, producing a magnetic field around the planet.
- What evidence suggests the Earth's core is magnetic?
- The consistent north-south behaviour of a compass anywhere on the Earth's surface.