Question

You are given a closed circuit with radii a and b as shown in figure, carrying current i. The magnetic dipole moment of the circuit is

• A. (a) p(a^2 + b^2) I
• B. $\frac { 1 } { 2 }$p(a^2 + b^2) i
• C. p(b^2 – a^2) I
• D. $\frac { 1 } { 2 }$p(b^2 – a^2) i

Answer 1

Answer: (B)

$\frac { 1 } { 2 }$p(a^2 + b^2) i

Answer 2

M = IA = I $\left( \frac { \pi \mathrm { a } ^ { 2 } } { 2 } + \frac { \pi \mathrm { b } ^ { 2 } } { 2 } \right)$