Answer
Correct Answer is A (A. curved lines from the north pole of the magnet to the south pole)
Explanation:
Any magnetic material like bar magnet always have pairs of poles that is North and South and these poles are connected together physically.
like poles always repels each other it means North pole always repels a north pole and south pole always repels south pole.
Opposite poles attract each other it means north pole attracts a South pole.
Magnetic field lines shows the direction of magnetic field at any point. magnetic lines of force point from the north pole to the south pole outside the magnet and these magnetic lines do not end at the tip of the magnet. They go inside the magnet and inside bar magnet the magnetic field points from the south pole to the north pole.
If we Place a magnetic compass(Magnetic compass needles point north and south in response to the Earth's magnetic field) at one pole of the magnet that time the needle will get deflected due to bar magnet(As North pole repels North pole of magnetic needle of compass and south pole of bar magnet will attract the north pole of magnetic needle of compass) and it will show the direction of magnetic field at that point where compass is kept. Make a dot next to compass in the direction the compass arrow(needle) points.
Again place the compass in such a way that the base of the arrow is at the dot you've just made. Again magnetic needle of compass will get deflected due to north poles of bar magnet. Now make a new dot where the tip of the arrow is pointing this time.
Keep doing this until you reach the other end of the magnet.
Now Connect all the dots. and these connecting dots will represents the magnetic field lines and these lines are curved lines from the north pole of the magnet to the south pole.
