Magnetic Fields: Start Here
Magnetic Fields: Start Here
- A magnet can pull a paper clip without touching it. It can also turn a compass needle from a distance.
- The magnet changes the space around it. We call this changed region a magnetic field.
A force can act without contact
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- A compass is a small magnet. Its north end points along the magnetic field at its position.
- A field line shows the direction of the force on a free magnetic north pole. The line is a model; it is not a physical wire or path.
- Outside a magnet, field lines point from the north pole to the south pole. Closely spaced lines show a stronger field.
A field lets one object exert a force on another object without touching it.
The exam definition
Definition
2 marksWhat is meant by magnetic field?
Model answer: A region where a force acts on a current-carrying conductor, a moving charge, or a magnetic material or magnetic pole.
A recent two-mark scheme gave one mark for “a region where a force acts” and one mark for one named object on which the force acts (9702/41/M/J/23 Q6(a)).
What produces a magnetic field
- A permanent magnet produces a magnetic field.
- Moving electric charge also produces a magnetic field. A current is moving charge, so every current-carrying wire has a field around it.
- The next lesson shows the three current patterns required by the syllabus.