Q. Which of the following graph represents the variation of magnetic flux density B with distance $r$ for a straight long wire carrying an electric current?
A) [image:4_image35.emf]
B) [image:4_image36.emf]
C) [image:4_image37.emf]
D) [image:4_image38.emf]
Explanation
(c) Magnetic field induction at a point due to a long current carrying wire is related with distance $r$ by relation $B \propto 1/r$. Therefore graph (c) is correct.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.