The correct option is Both A and R are true but R is NOT the correct explanation of A
Explanation
Magnetic field lines are imaginary lines used to represent the direction and strength of a magnetic field. A fundamental property of magnetic field lines is that they form continuous closed loops, unlike electric field lines which originate from positive charges and terminate on negative charges.
Statement-wise Analysis:
- Assertion (A): Correct. Outside a bar magnet, magnetic field lines emerge from the North pole and merge at the South pole. However, because magnetic monopoles do not exist and magnetic field lines must form continuous closed loops, the lines travel from the South pole to the North pole inside the body of the magnet.
- Reason (R): Correct. It is a fundamental law of magnetism that like magnetic poles repel each other and unlike magnetic poles attract each other.
Reasoning for Both A and R are true but R is NOT the correct explanation of A
While both statements are factually correct, the Reason (R) does not explain the Assertion (A). The direction of magnetic field lines inside the magnet is governed by the solenoidal nature of the magnetic field (Gauss’s Law for Magnetism, which implies $\nabla \cdot \mathbf{B} = 0$), requiring lines to be continuous loops. The attractive or repulsive force between poles is a separate interaction property and does not define the internal path of the field lines.
Key Takeaway:
Magnetic field lines form continuous closed loops; they run from North to South outside the magnet and from South to North inside the magnet.