11-05-2012, 04:53 PM
Magnetostatics
awp magnetic.pdf (Size: 202.92 KB / Downloads: 115)
Electric charges are source of electric fields. An electric field exerts force on an
electric charge, whether the charge happens to be moving or at rest.
One could similarly think of a magnetic charge as being the source of a magnetic
field. However, isolated magnetic charge ( or magnetic monopoles) have never
been found to exist. Magnetic poles always occur in pairs ( dipoles) – a north
pole and a south pole. Thus, the region around a bar magnet is a magnetic field.
What characterizes a magnetic field is the qualitative nature of the force that it
exerts on an electric charge. The field does not exert any force on a static charge.
However, if the charge happens to be moving (excepting in a direction parallel to
the direction of the field) it experiences a force in the magnetic field.
It is not necessary to invoke the presence of magnetic poles to discuss the source
of magnetic field. Experiments by Oersted showed that a magnetic needle gets
deflected in the region around a current carrying conductor. The direction of deflection
is shown in the figure below.
Current