Q. A thick current carrying cable of radius 'R' carries current 'I' uniformly distributed across its cross-section. The variation of magnetic field B(r) due to the cable with the distance 'r' from the axis of the cable is represented by:
A) [image:2021_Q171_opt_a.png]
B) [image:2021_Q171_opt_b.png]
C) [image:2021_Q171_opt_c.png]
D) [image:2021_Q171_opt_d.png]
Explanation
[Solution] Inside, $B \propto r$ (linear rise up to r = R); outside, $B \propto 1/r$. Graph (b) shows this. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.