Are field lines from a magnetic dipole equal in magnitude?

1. Jul 14, 2015

Luke Cohen

http://www.physics.sjsu.edu/becker/physics51/images/28_03_Earth_magnetic_field.jpg
If this is your magnetic dipole and you start at the north end and follow a field line to the south end, is the magnetic field equal in magnitude the entire way through?

2. Jul 14, 2015

Dr. Courtney

No. Magnetic field strength is more like the density of field lines.

3. Jul 14, 2015

Luke Cohen

What if you had a magnet and drew a circle from the north to the south pole. This circle had the same radius from the center of the magnet.

4. Jul 14, 2015

Dr. Courtney

It depends on how closely the magnetic field is approximated as a pure dipole field.

In a pure dipole field, the field strength is equal in magnitude at points symmetric wrt the N and S poles.

Some magnetic sources are better approximated as pure dipoles than others.

5. Jul 14, 2015

nasu

The strength of the field does not have spherical symmetry for a magnet.
The radius from the center is not enough to determine the value.