Electricity and Magnetism : AC - DC Generators / A Series/Parallel Circuit Puzzle / Circle of Magnetism / Dynamo 1/ Dynamo 2 / Induced Current - Eddy Currents / Lenz's Law / The Magnetic Field - Lines of Force / The Rotating Copper Disk / Pepsi Can / Helmholtz Coils / Electrons Beam
The Magnetic Field - Line of Force

The plastic box contains small iron rods that are free to rotate so that they can align themselves long  the direction of the  magnetic field  B.

When the plastic box is moved around and in between the pole faces of the magnet, we can observe the lines of magnet force. That lines of magnetic force are curved, and go from one pole of the magnet to the other pole. The outside lines are more curved than the ones near the poles.

WHAT IS IT ANYHOW?

The magnetic field is an abstract idea that describes the space in the vicinity of the magnet. At every point in space the pole of a small magnet experiences a force which has a particular size and direction. There are no actual lines in the space, but one can draw lines that show the direction of the force at every point in space.