Sachin Tyagi
Last Activity: 15 Years ago
So far we have discussed the field of magnetic dipole only at the point on the axis. now we consider the complete magnetic dipole field. In the case of the electric dipole, a complete patter of field lines was discussed earlier. That can be compared with the field lines for a current loop shown in given figure. You can see a great similarity between patterns of field lines outside the loop. Another similarity between the electric and magnetic dipole fields is that both vary as r-3 when we are far from the dipole. A significant difference between electric and magnetic field lines is that electric field lines start on positive charges and end on negative charges, whereas magnetic field lines always from closed loops.
Figure shows:- (a) The electric field of an electric dipole (b) The dipole magnetic field of a current loop. (c) The dipole magnetic field of a bar magnet. The dashed lines show the field lines inside the magnet.
Figure shows the field lines of a bar magnet. It shows the same pattern of field lines as the current loop, so a bar magnet can also be considered to be a magnetic dipole. It is convenient to label the two ends of a bar magnet as the north (N) and south (S) poles, with field lines leaving the N pole and converging on the S pole. Superficially the poles may seem to behave like the positive and negative charges of an electric dipole. However, close inspection of the figure shows that the field lines do not start and end on the poles but instead continue through the interior of the magnet, again forming closed loops. The n and S poles do not behave like the charges in an electric dipole, and as we discuss earlier, isolated magnetic poles do not appear to exist in nature.
