Magnetic fields
A Area surrounding a magnet that can exert a force on magnetic materials. is the region around a magnet where a force acts on another magnet or on a magnetic material.
Detecting magnetic fields
A magnetic field is invisible, but it can be detected using a magnetic compass. A compass contains a small bar magnet on a pivot so that it can rotate. The compass needle points in the direction of the Earth鈥檚 magnetic field, or the magnetic field of a magnet.
Magnetic fields can be mapped out using small Small magnetic compass used to detect magnetic fields.:
- Place the plotting compass near the magnet on a piece of paper.
- Mark the direction the compass needle points.
- Move the plotting compass to many different positions in the magnetic field, marking the needle direction each time.
- Join the points to show the field lines.
The needle of a plotting compass points to the south pole of the magnet.
The behaviour of a compass shows that the Earth has a magnetic field. The Earth鈥檚 core, which is made from iron and nickel, produces this magnetic field.
Drawing a magnetic field
The diagram shows the magnetic field around a bar magnet
The diagram shows these key features:
- the An imaginary line which indicates the direction of force caused by a magnet. An arrow on the line shows the force direction on a magnetic north pole, so points from north to south. never cross each other
- the closer the lines, the stronger the magnetic field
- the lines have arrowheads to show the direction of the force exerted on a magnetic north pole
- the arrowheads point from the north pole of the magnet to its south pole