AP EAPCET 20-Aug-2021 Shift 1 Paper

Given,
Length of wire =L
Current through wire =I
∵ Magnetic moment, m= Current (I)×Area(A) ...(i)
and since circle of radius r is made of wire of length L
∴2πr=L⇒r=

L

2π

So, area, A=πr2 =π(

L

2π

)2=

L2

4π

Put this value in Eq. (i), we get
m=

IL2

4π