Magnetic field lines
An object that produces a magnetic field which pulls on other magnetic materials and attracts or repels other objects. create magnetic fields. These magnetic fields cannot be seen. They fill the space around a magnet where the magnetic forces work, and where they can attract or repel magnetic materials.
Finding magnetic fields
Although we cannot see magnetic fields, we can detect them using iron filings. The tiny pieces of iron line up in a magnetic field.
Drawing magnetic field diagrams
It would be difficult to draw the results from the sort of experiment seen in the photograph, so we draw simple magnetic field lines instead.
In the diagram, note that:
- the field lines have arrows on them
- the field lines come out of N (north pole) and go into S (south pole)
- the field lines are more concentrated at the Either of the two points of a magnet to and from which the lines of magnetic force are directed.
The magnetic field is strongest at the poles, where the field lines are most concentrated.
Two bar magnets
The magnetic field pattern when two magnets are used is shown in this diagram.
Note the different patterns seen when two like poles are used and two opposing poles are used.
Uniform magnetic field
When magnetic field lines are the same distance apart from each other, we say that the magnetic field is uniform.
This is shown in the diagram below.
The following information on this page is for higher tier students only.
To calculate the strength of a magnetic force on a wire you must find the This is the amount of flux passing through an unit area at a right angle to the magnetic field lines. It is measured in Tesla (T).. This is measured in a unit called tesla. Lines are drawn to show the direction on a magnet’s north pole. They are called lines of magnetic flux, and are shown in the diagram. The magnet in diagram B is stronger than the magnet in diagram A. More lines means a stronger attractive force.