The direction of magnetic field lines inside a bar-magnet is

CONCEPT:

• Bar Magnet: A bar magnet consists of two equal and opposite magnetic pole separated by a small distance. Poles are not exactly at the ends.
• The shortest distance between two poles is called effective length (L_e) and is less than its geometric length (L_g) for bar magnet.
• Magnetic field and magnetic lines of force: It is the space around a magnetic pole or magnet or current-carrying wire within which it's magnetic effect can be experienced is defined as a magnetic field.

• The magnetic field can be represented with the help of a set of lines or curves called magnetic lines of force.

EXPLANATION:

• The direction of magnetic field lines outside a bar-magnet is from North pole to south pole while inside the magnet it is from south pole to north pole. Hence option 1 is correct.

• The degree of closeness of the magnetic field line determines the strength of the magnetic field. Stronger is the field at places where field lines are crowded.