Q.
A long wire carrying a steady current is bent into a circular loop of one turn. The magnetic field at the centre of the loop is B. It is then bent into a circular coil of n turns. The magnetic field at the centre of this coil of n turns will be
A) nB
B) $n^2B$
C) 2nB
D) $2n^2B$
Explanation
[Solution] Radius becomes r/n with n turns: $B' = \frac{\mu_0 nI}{2(r/n)} = n^2B$. Answer (2).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.