Monday, March 23, 2009

The Magnetic Field

The type of magnet with which we are most familiar is the
bar-magnet. Iron filings sprinkled around a bar-magnet form
a suggestive pattern similar to the lines of force about an electric
dipole. The end of a bar-magnet that points itself toward the
north geographical pole is labeled the north pole of the magnet
and opposite end is called the south pole. It is readily seen the
like poles repel and unlike poles attract. The tendency of a
magnet to align itself in a north-south direction indicates that the
Earth acts as if a bar magnet is located at the center of the Earth
and aligned (almost) with the Earth’s rotation axis and with the
north geographical pole coinciding with the Earth’s south magnetic

While there seem to be many similarities electrical and magnetic
forces, there is one very fundamental difference. If we cut a bar
magnet in half we do not get isolated north and south poles.
Instead we get two bar magnets each with a north and south pole.
This observation has never been violated experimentally. That is,
we have never observed a magnetic monopole. We will later
formulate this observation into the second of Maxwell’s equations.

1.Magnetic Force on a Straight Current Carrying Wire

- Units
- Direction
- General Curves and Variable Field

2. Magnetic Force on a Moving Charge

3. Lorentz Force

4. Work Done on a Moving Particle by a Magnetic Force

5. Particle Motion in a Magnetic Field

6. Torque on a Current Loop

7. Potential Energy of a Magnetic Dipole

More ( pdf )

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