A 2 amp current is flowing through two different small circular copper coils having radii ratio $1:

Question

A 2 amp current is flowing through two different small circular copper coils having radii ratio $1: 2$. The ratio of their respective magnetic moments will be

Professor PC Thomas Classes · Answer

(c) : Magnetic moment, $M=I A$ $ 	herefore \frac{M_1}{M_2}=\frac{I 	imes \pi r_1^2}{I 	imes \pi r_2^2}=\frac{r_1^2}{r_2^2} \quad 	ext { or } \quad \frac{M_1}{M_2}=\left(\frac{1}{2}ight)^2=\frac{1}{4} $