Which one of the following graphs shows the magnetic field B inside and outside a current carrying long straight wire of a circular cross section of radius R (current uniformly distributed)?

Correct option is D

Correct answer is d
Concept:
A current-carrying wire generates a magnetic field both inside and outside the wire.
Inside the wire (r ≤ R), the magnetic field increases linearly with the distance from the center of the wire.
Outside the wire (r > R), the magnetic field decreases inversely with the distance.
At r = R, the magnetic field reaches its maximum value.
Explanation:
Inside the wire (r ≤ R):
The magnetic field is proportional to r, so B ∝ r.
Outside the wire (r > R):
The magnetic field follows an inverse relationship with r, so B ∝ 1/r.
Hence, the graph must show:
A linear increase inside the wire (from r = 0 to r = R).
A sharp decrease outside the wire (for r > R).