Edexcel iGCSE Physics -6.4 Magnetic Field Lines- Study Notes- New Syllabus
Edexcel iGCSE Physics -6.4 Magnetic Field Lines- Study Notes- New syllabus
Edexcel iGCSE Physics -6.4 Magnetic Field Lines- Study Notes -Edexcel iGCSE Physics – per latest Syllabus.
Key Concepts:
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Magnetic Field Lines
A magnetic field describes the region around a magnet where magnetic forces act. Magnetic field lines are used as a model to show the shape, direction, and strength of a magnetic field.
Magnetic Field Line – Definition
Definition: A magnetic field line is an imaginary line drawn to show the direction in which a north pole would move if placed in a magnetic field.
Key idea: Magnetic field lines are a visual model — they help us understand magnetic fields but are not physical objects.
Direction of Magnetic Field Lines
- Outside a magnet, field lines go from the north pole to the south pole.
- Inside a magnet, field lines go from the south pole back to the north pole.
- This forms a continuous closed loop.
Strength of a Magnetic Field
The strength of a magnetic field depends on how close together the field lines are.
- Field lines close together → strong magnetic field.
- Field lines far apart → weak magnetic field.
Key point: Field lines are closest near the poles, showing that the magnetic field is strongest there.
Rules for Drawing Magnetic Field Lines
- Field lines never cross.
- Arrows show the direction from north to south.
- Lines form closed loops.
- The pattern is symmetrical around a bar magnet.
Magnetic Field Lines and Forces
Magnetic field lines help explain attraction and repulsion:
- Opposite poles → field lines connect smoothly.
- Like poles → field lines repel and bend away from each other.
Summary
- A magnetic field line shows the direction of a magnetic field.
- Direction is from north to south outside the magnet.
- Spacing of lines shows field strength.
- Field lines never cross.
Example
A student draws magnetic field lines around a bar magnet and notices that the lines are closer together near the poles than near the centre. Explain what this shows about the magnetic field.
▶️ Answer / Explanation
- Magnetic field strength depends on the spacing of field lines.
- Closer field lines indicate a stronger magnetic field.
- The field is strongest near the poles of the magnet.
- The field is weaker near the centre of the magnet.
Example
Two bar magnets are placed close together with their north poles facing each other. Describe and explain the pattern of magnetic field lines between the magnets.
▶️ Answer / Explanation
- Both facing poles are north poles.
- Like poles repel each other.
- Magnetic field lines bend away from the region between the poles.
- No field lines connect directly between the two north poles.
- This pattern shows magnetic repulsion.