Direction of field inside and outside a magnetic dipole

[Amith2006]

Homework Statement

1) In the case of a bar magnet, outside it, the magnetic lines of forces start from North Pole and end on South Pole. But inside it, the lines of force start from south and end on North Pole. According to definition of direction of lines of force, it is the direction in which a unit north pole would move when placed in a magnetic field. This is true outside the bar magnet but not so inside it. Is the rule applicable only outside the body of the bar magnet?
2) Now, it is a known fact that a circular current carrying conductor acts like a magnetic dipole(bar magnet). If on placing the coil with one of its side facing you, and the current flows in clockwise direction, then that side acts like a south pole and the other side acts like North Pole. At the centre of the coil, will the direction of field be from north to south or south to North Pole? I have this doubt because inside the bar magnet the field is in one direction while outside the field is in opposite direction.

Homework Equations

The Attempt at a Solution

 

[ranger]

In the case of a bar magnet, outside it, the magnetic lines of forces start from North Pole and end on South Pole. But inside it, the lines of force start from south and end on North Pole. According to definition of direction of lines of force, it is the direction in which a unit north pole would move when placed in a magnetic field. This is true outside the bar magnet but not so inside it. Is the rule applicable only outside the body of the bar magnet?

The field lines travel in closed loops i.e loops don't start or stop at any point, or even cross paths. This would explain why its south to north inside the bar magnet.

Now, it is a known fact that a circular current carrying conductor acts like a magnetic dipole(bar magnet). If on placing the coil with one of its side facing you, and the current flows in clockwise direction, then that side acts like a south pole and the other side acts like North Pole. At the centre of the coil, will the direction of field be from north to south or south to North Pole? I have this doubt because inside the bar magnet the field is in one direction while outside the field is in opposite direction.

For current flowing in a conductor, the field lines are circles around the conductor. They don't start from north to south for example.
http://www.uvi.edu/Physics/SCI3xxWeb/Electrical/BfieldLoop.gif

 

[m2003]

The direction of the magnetic field lines inside and outside a magnetic dipole, such as a bar magnet or a circular current carrying conductor, can be determined by the right-hand rule. When using the right-hand rule, the fingers of the right hand point in the direction of the current flow, and the thumb points in the direction of the magnetic field lines.

In the case of a bar magnet, the direction of the magnetic field lines outside the magnet is from the north pole to the south pole. This is because the magnetic field lines always flow from the north pole to the south pole. However, inside the bar magnet, the direction of the magnetic field lines is from the south pole to the north pole. This may seem counterintuitive, but it is due to the fact that the magnetic field lines always form closed loops and must flow from the north pole to the south pole inside the magnet.

For a circular current carrying conductor, the direction of the magnetic field lines at the center of the coil will depend on the direction of the current flow. If the current flows clockwise, the direction of the magnetic field at the center of the coil will be from the north pole to the south pole. If the current flows counterclockwise, the direction of the magnetic field will be from the south pole to the north pole. This is consistent with the direction of the magnetic field lines inside and outside a bar magnet.

In summary, the direction of the magnetic field lines inside and outside a magnetic dipole follows the right-hand rule and is consistent with the direction of the magnetic field lines in a bar magnet. This rule is applicable both inside and outside the body of the bar magnet, as well as for other types of magnetic dipoles.