MAGNETISM

One of the first things we note in examining a bar magnet is that it has two region of magnetic concentration: poles at the ends of the magnet. We call these two poles north seeking N, and south seeking, S, since a compass needle was one of the earliest applications of magnetism. The N pole of a magnet, like a compass, points north, and the S pole points south.

That is, N-S, attract, and N-N or S-S poles repel each other. The strength of the attraction or repulsion relies on the strength of the magnetic poles. Furthermore, in a manner similar to Coulomb's law, the strength of the magnetic force is inversely proportional to the distance between the magnetic poles.

Each magnet produces a force on every other magnet. In order to discuss these force effects; we present the concept of a magnetic field. A magnetic field is a set of imaginary lines that indicates the direction a small compass needle would point if it were placed at a specific spot. If you are to look at a magnetic field, the arrows in the field lines indicate the direction in which a compass N pole would point. The closer together the field lines, the stronger the magnetic force is acting on the imaginary compass.

The field concept too applies to the electric force. An electric field is a set of imaginary lines that indicates the direction a small positive charge would move if it were placed at a specific spot. The electric fields are indicated in the diagram above for a single positive charge, a single negative charge, and a positive and negative charge together. The last arrangement is called an electric dipole because there are two poles involved.

 For single negative and positive charges, the field lines are directed as shown above . For an electric dipole, which is a positive and negative charge together, the field lines start at the positive charge and end at the negative charge.

The field concept too applies to the electric force. An electric field is a set of imaginary lines that indicates the direction a small positive charge would move if it were placed at a specific spot. The electric fields are indicated in the diagram above for a single positive charge, a single negative charge, and a positive and negative charge together. The last arrangement is called an electric dipole because there are two poles involved.