Q. The magnetic moment of a circular coil carrying current is
A) Directly proportional to the length of the wire in the coil
B) Inversely proportional to the length of the wire in the coil
C) Directly proportional to the square of the length of the wire in the coil
D) Inversely proportional to the square of the length f the wire in the coil
Explanation
(c) $M = NiA\ \Rightarrow M \propto A \Rightarrow M \propto r^{2}\ \lbrack$As $I = 2\pi r \Rightarrow l \propto r\rbrack$
$\Rightarrow M \propto l^{2}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.