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Magnetic field lines
Beginner
Lines run from north to south outside the magnet.
Field lines show the direction a north pole would be pushed; they leave north poles, enter south poles, and form closed loops. Denser lines mean a stronger field.
Iron filings reveal the pattern around a bar magnet.
Field lines never cross.
In more detail
Magnetic field lines show the direction of the field, running from north to south outside a magnet and forming closed loops. The line density indicates field strength.
Real-world uses
- Engineers sketch field lines to design motors and transformers.
- Iron filings reveal field line patterns in physics demonstrations.
- Iron filings sprinkled over a bar magnet line up along the field lines, revealing the pattern of the field.
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Frequently asked questions
Do field lines start and end anywhere?
No, they form closed loops, because there are no magnetic monopoles.
Do field lines cross?
No, because the field has a single direction at each point.
Do field lines start or end anywhere?
They form closed loops and run from north to south outside a magnet, passing through it back to the start.
Related topics in Magnetism & Induction
Magnets and poles · Earth's magnetic field · Magnetic force on a moving charge · Circular motion in B field