Magnetism and magnetic fields — OCR GCSE Physics
In summary: Magnetism and magnetic fields is a key topic in OCR GCSE Physics. Key exam tip: Ensure you can draw accurate magnetic field patterns for bar magnets and current-carrying wires
Exam Tips for Magnetism and magnetic fields
- Ensure you can draw accurate magnetic field patterns for bar magnets and current-carrying wires
- Remember that field line density represents field strength
- Be prepared to explain how a dipping compass provides evidence for Earth's magnetic core
- Practice applying Fleming's left-hand rule to various orientations of wires and fields
- Ensure you can distinguish between the function of step-up and step-down transformers
- Be prepared to perform calculations involving the transformer turns ratio equation
- Use clear, scientific terminology when describing energy transfers in loudspeakers and microphones
Common Mistakes
- Assuming larger magnets are always stronger
- Misunderstanding field line density as an indicator of field strength
- Failing to recognize that geographic and magnetic poles are not in the same location
- Difficulty visualizing the three-dimensional nature of Fleming's left-hand rule
- Misunderstanding the role of the commutator in D.C. motors
- Superficial understanding of how changing magnetic fields induce current in transformers
Marking Points
- Attraction and repulsion between like and unlike poles
- Differences between permanent and induced magnets
- Magnetic field patterns around bar magnets and current-carrying wires
- Relationship between field strength and distance from a conductor
- Use of solenoids to enhance magnetic effects
- Evidence for Earth's magnetic core using dipping compasses
- Fleming's left-hand rule orientation (force, current, magnetic field)
- Calculation of force on a conductor using F = BIl
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