Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Magnetic field lines do not cross each other.
Reason (R): The tangent to the field line at a given point represents the direction of the net magnetic field at that point.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → Both (A) and (R) are correct and (R) is the correct explanation of (A).
Assertion (A) Magnetic field lines do not cross each other. — True. Two magnetic field lines never meet or cross at any point.
Reason (R) The tangent to the field line at a given point represents the direction of the net magnetic field at that point. — True. A field line is drawn so that at every point it runs along \( \mathbf{B} \) there.
Why Reason (R) explains Assertion (A)?
If two lines crossed, there would be two tangents at the point of crossing, one for each line.
By R, these two tangents would give two different directions of the field at the same point. The field at a point has only one direction, so the lines cannot cross.
NCERT (2026-27):
The magnetic field lines – “(ii) The tangent to the field line at a given point represents the direction of the net magnetic field B at that point.”
The magnetic field lines – “(iv) The magnetic field lines do not intersect, for if they did, the direction of the magnetic field would not be unique at the point of intersection. …”