Inside a bar magnet, the magnetic field lines
A. are not present
B. are parallel to the cross-sectional area
C. are in direction from N-poles to S-poles
D. are in the direction from S-pole to N-pole.

Hint: A bar magnet has two poles. The magnetic field lines emerge from the north pole and enter the south pole. Find out the properties of the magnetic field lines. From the properties of the magnetic field line we can give our answer.

Complete answer:
A bar magnet is a rectangular piece of metal with permanent magnetic properties. Permanent magnets are made of ferromagnetic materials. A bar magnet has two poles – north pole and south pole. Magnetic field lines are the imaginary lines which give the direction of the magnetic field.



The magnetic field lines for a bar magnet emerges from the north pole and enters the south pole.
The properties of these magnetic field lines are that it always emerges from the north pole of the magnet and enters the south pole. The magnetic field lines do not cross each other and they always form a closed loop.

Since the magnetic field lines form a closed loop, the magnetic field lines for a bar magnet will also form a closed loop. So, the magnetic field line will emerge from the north poles and enter the south pole and to form a closed loop, inside the bar magnet, the magnetic field lines will travel from the south pole to the north pole to complete the closed loop.

So, the correct answer is “Option d”.

Note:
All the magnetic field lines always form closed loops. If we consider a current carrying solenoid, it will create a magnetic field. Here also we get a magnetic field in a closed loop. Compared to this example, we can also give our answer for the above equation.