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4.Moving Charges and Magnetism
medium
The magnetic moments associated with two closely wound circular coils $A$ and $B$ of radius $r_A=10 cm$ and $r_B=20 cm$ respectively are equal if: (Where $N _A, I _{ A }$ and $N _B, I _{ B }$ are number of turn and current of $A$ and $B$ respectively)
A
$2 N _{ A } I _{ A }= N _{ B } I _{ B }$
B
$N _{ A }=2 N _{ B }$
C
$N _{ A } I _{ A }=4 N _{ B } I _{ B }$
D
$4 N _{ A } I _{ A }= N _{ B } I _{ B }$
(JEE MAIN-2023)
Solution
$M = NIA$
$M _{ A }= M _{ B }$
$N _{ A } I _{ A } A _{ A }= N _{ B } I _{ B } A _{ B }$
$N _{ A } I _{ A } \pi(0.1)^2= N _{ B } I _{ B } \pi(0.2)^2$
$N _{ A } I _{ A }=4 N _{ B } I _{ B }$
Standard 12
Physics
